http://www.gemologyproject.com/wiki/api.php?action=feedcontributions&user=Nick+Lombard&feedformat=atomThe Gemology Project - User contributions [en]2024-03-29T06:15:40ZUser contributionsMediaWiki 1.28.0http://www.gemologyproject.com/wiki/index.php?title=Template:Malachite&diff=7553Template:Malachite2008-01-21T03:25:09Z<p>Nick Lombard: </p>
<hr />
<div>{| align=right width=250px {{table}}<br />
|-<br />
! colspan=2 | Malachite<br />
|-<br />
| Chemical composition || Cu<sub>2</sub>(CO<sub>3</sub>)(OH)<sub>2</sub><br />
|-<br />
| Colors || Banded light and dark green<br />
|-<br />
| Crystal system || [[Crystals_&_Their_Structure#Monoclinic_Crystal_System | Monoclinic]]<br />
|-<br />
| Habit || Botryoidal, stalactitic, globular<br />
|-<br />
| Cleavage || Distinct<br />
|-<br />
| Fracture || Conchoidal, splintery<br />
|-<br />
| Hardness || 3.5-4<br />
|-<br />
| Optic nature || Biaxial -<br />
|-<br />
| Refractive index || 1.655 - 1.909<br />
|- <br />
| Birefringence || 0.254<br />
|-<br />
| Dispersion || Weak<br />
|- <br />
| Specific gravity || 3.60 - 4.05<br />
|-<br />
| Lustre || Dull, silky, vitreous<br />
|-<br />
| Transparency || Translucent to opaque<br />
|-<br />
| Pleochroism || None<br />
|-<br />
| Sources || Australia, Namibia, Russia, USA, Zambia, Zaire<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Malachite&diff=7552Malachite2008-01-21T03:09:29Z<p>Nick Lombard: </p>
<hr />
<div> {{malachite}}<br />
<br />
==Sources==<br />
<br />
* ''Gemstones - Properties, identification and use'' (2008) - Arthur Thomas ISBN 9781845376024</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Cleavage&diff=7525Cleavage2007-12-24T09:10:22Z<p>Nick Lombard: /* Cleavage */ Spelling fix</p>
<hr />
<div>__forcetoc__<br />
<br />
==Cleavage==<br />
Cleavage is the splitting of a gemstone along the direction of its crystal faces where atoms have weaker bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction. The result of cleavage is a more or less flat plane with often a silky luster.<br /><br />
Cleavage is a reproducable property of a gemstone and can be done at any point of the cleavage direction.<br />
<br />
There are several directions of cleavage.<br />
* Prismatic cleavage<br />
* Basal cleavage<br />
* Pinacoidal cleavage<br />
* Octahedral cleavage <br />
* Rhombohedral cleavage<br />
<br />
The quality of cleavage is expressed with a few simple phrases.<br />
* Perfect<br />
* Good (or imperfect)<br />
* Fair (or moderate)<br />
* Poor (or weak)<br />
* None<br />
<br />
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]<br />
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]<br />
<br clear=all><br />
Stones and their cleavage directions:<br />
<br />
{| {{table}} width="50%"<br />
|-<br />
! Cleavage || Directions || Stones || Quality<br />
|-<br />
| align=center| Basal <br />
| align=center| 1 <br />
| align=center| [[Topaz]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Beryl]]<br />
| align=center| Imperfect<br />
|-<br />
| align=center| Prismatic <br />
| align=center| 2 <br />
| align=center| [[Peridot]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Spodumene]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Chrysoberyl]]<br />
| align=center| Weak to Moderate<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Diopside]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Cubic <br />
| align=center| 3 <br />
| align=center| [[Halite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Rhombohedral <br />
| align=center| 3 <br />
| align=center| [[Calcite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Rhodochrosite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Octhahedral <br />
| align=center| 4 <br />
| align=center| [[Fluorite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Diamond]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Dodecahedral <br />
| align=center| 6<br />
| align=center| [[Sphalerite]]<br />
| align=center| Perfect<br />
|}<br />
<br clear=all><br />
<br />
==Parting==<br />
<br />
Parting is the splitting of a gemstone along twinning or pressure planes.<br /><br />
Although this is similar to cleavage, parting can only be done along certain, well defined, planes of weakness and it is not reproducable like cleavage. Usually these parting planes are created during growth of a crystal when pressure was applied to the crystal causing it to (partially) break or fracture. Later overgrowth then heals the fracture, leaving a weak area inside.<br />
<br />
One of the most profound examples of parting is mica which concists of many very thin layers that can be easily parted with the fingernail. It is this mineral that is traditionally used for [[Polariscope#Quarter_wave_plates|quarter wave plates]].<br />
==Fracture==<br />
<br />
Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object along a direction other than then the direction of cleavage or parting. The most common type of fracture is termed "conchoidal" (shell-like).<br /><br />
<br />
The types of fracture are:<br />
* conchoidal<br />
* uneven<br />
* even<br />
* splintery<br />
* granular<br />
<br />
<br />
==Sources==<br />
<br />
* ''Gemmology'' (2005) - Peter Read<br />
<br />
==External links==<br />
<br />
* [http://www.galleries.com/minerals/property/parting.htm Parting]<br />
* [http://www.galleries.com/minerals/property/cleavage.htm Cleavage]</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Table_Of_Contents&diff=7511Table Of Contents2007-12-22T08:26:23Z<p>Nick Lombard: Added link to calcite</p>
<hr />
<div>In this TOC (Table Of Contents) you will find pages that have been published presented in blue and pages that yet need to be written presented in red. For better navigation, we list the pages in 3 categories:<br />
#Theory - Basic and in-depth mechanisms involved in gemology<br />
#Practical - Descriptions of instruments, techniques and other practical discussions<br />
#Gemstones - Information about the gemstone at hand<br />
<br />
For the neophyte it is best to start in that order as some words and principles introduced in the theory pages will need to be understood first. At the very least, one should learn the theory in the "basic" sections of the pages.<br /><br />
Although gemology is not rocket science, some science and math is involved. We don't believe in the dumbing-down of gemology, so you should be ready and willing to expand your horizons. If you find any of the technical concepts difficult to visualize or grasp, go to the forum (the link is above) and ask. We will help you with it, and at the same time you will help this project become more complete for those who come after you. <br />
<br />
We never said it was going to be easy. But it's a heck of an interesting ride.<br />
<br />
<br />
{| {{toctable}} width="100%"<br />
<br />
!Theory <br />
!Practical<br />
!Gemstones<br />
<br />
|-<br />
<br />
|style="padding-right:5px" valign="top"|<br />
:'''Content'''<br />
#[[Introduction to Gemology]]<br />
##[[Introduction_to_Gemology#Education|Education]]<br />
##[[Glossary of Terms]]<br />
#[[Origins of minerals]]<br />
##[[Origins_of_minerals#Igneous_.28Magmatic.29_rocks|Igneous rocks]]<br />
##[[Origins_of_minerals#Sedimentary_rocks|Sedimentary rocks]]<br />
##[[Origins_of_minerals#Metamorphic_rocks|Metamorphic rocks]]<br />
#[[The Chemistry of Gemstones]]<br />
##[[Isomorphous replacement]]<br />
##[[The Chemical Classification of Gems & Minerals]]<br />
#[[Crystallography]]<br />
##[[Crystal Systems]]<br />
##[[Form]]<br />
##[[Habit]]<br />
##[[Symmetry]]<br />
##[[Twinning]]<br />
#[[Cleavage]]<br />
#[[Cleavage#Parting|Parting]]<br />
#[[Cleavage#Fracture|Fracture]]<br />
#[[Optical properties of gemstones]]<br />
##[[Nature of light]]<br />
###[[Nature_of_light#The_electromagnetic_wave_theory |The electromagnetic wave theory]]<br />
###[[Nature_of_light#The_quantum_theory |The quantum theory]]<br />
###[[Nature_of_light#The_electromagnetic_spectrum |The electromagnetic spectrum]]<br />
##[[Reflection]]<br />
###[[Luster]]<br />
###[[Sheen]]<br />
####[[Sheen#Chatoyancy | Chatoyancy]]<br />
####[[Sheen#Asterism | Asterism]]<br />
####[[Sheen#Iridescence | Iridescence]]<br />
###[[Brilliance | Brilliance (Total Internal Reflection)]]<br />
##[[Polarization]]<br />
##[[Pleochroism]]<br />
##[[Color]]<br />
###[[Color grading]]<br />
###[[Causes of color]]<br />
##[[Refraction]]<br />
###[[Double Refraction]]<br />
##[[Dispersion]]<br />
##[[Diffraction]]<br />
##[[Interference]]<br />
##[[Luminescence]]<br />
###[[Luminescence#Fluorescence | Fluorescence]]<br />
###[[Luminescence#Phosphorescence | Phosphorescence]]<br />
###[[Luminescence#Tenebrescence | Tenebrescence]]<br />
###[[Luminescence#Triboluminescence | Triboluminescence]]<br />
#[[Hardness]]<br />
#[[Specific Gravity]]<br />
#[[Math| Basic math for gemology]]<br />
##[[Math#Cross-multiplication | Cross-multiplication]]<br />
##[[Math#Sine.2C_cosine_and_tangent | Sine, cosine and tangent]]<br />
##[[Math#Degrees.2C_minutes_and_seconds | Degrees, minutes and seconds]]<br />
<br />
| style="padding-right:5px" valign=top|<br />
:'''Content'''<br />
#[[Equipment used to identify gemstones]]<br />
##[[10x Loupe]]<br />
##[[Spectroscope]]<br />
##[[Refractometer]]<br />
##[[Polariscope]]<br />
##[[Dichroscope]]<br />
##[[Immersion cell]]<br />
##[[Color Filters]]<br />
##[[Microscope]]<br />
##[[Hydrostatic Balance]]<br />
##[[Heavy Liquids]]<br />
##[[Hardness#Hardness_pencils|Hardness pencils]]<br />
#[[Inclusions]]<br />
#[[Synthetic gemstones]]<br />
#*Methods<br />
##[[Sublimation]]<br />
##[[Skull crucible]]<br />
##[[Flame fusion]] (Verneuil method)<br />
#*Gemstones<br />
##[[Synthetic forsterite]]<br />
##[[Synthetic moissanite]]<br />
##[[Synthetic cubic zirconia]]<br />
#[[Visual Optics]]<br />
##[[The Hodgkinson Method]]<br />
#[[Video presentations]]<br />
<br />
<br />
:'''Essays'''<br />
#[[essays:adding arrows|Adding arrows]]<br />
<br />
| style="padding-right:5px" valign=top|<br />
:'''Content'''<br />
*[[Alphabetic list by gemstone name]]<br />
#[[Diamond]]<br />
#[[Corundum]]<br />
##[[Ruby]]<br />
##[[Sapphire]]<br />
#[[Beryl]]<br />
##[[Aquamarine]]<br />
##[[Bixbite]]<br />
##[[Emerald]]<br />
###[[Vanadium Beryl]]<br />
##[[Goshenite]]<br />
##[[Green Beryl]]<br />
##[[Heliodor]]<br />
##[[Maxixe]]<br />
##[[Morganite]]<br />
##[[Riesling]]<br />
##[[True Blue]]<br />
##[[Pezzottaite]] (Beryl Group)<br />
#[[Quartz]]<br />
##[[Amethyst]]<br />
##[[Ametrine]]<br />
##[[Citrine]]<br />
##[[Prasiolite]]<br />
##[[Rock Crystal]]<br />
##[[Rose Quartz]]<br />
##[[Smokey Quartz]]<br />
#[[Quartz - Polycrystalline]]<br />
##[[Chalcedony]]<br />
###[[Agate]]<br />
###[[Arkansas stone]]<br />
###[[Bloodstone]]<br />
###[[Carnelian]]<br />
###[[Chrysoprase]]<br />
###[[Jasper]]<br />
###[[Onyx]]<br />
###[[Sard]]<br />
###[[Sardonyx]]<br />
###[[Tigereye]]<br />
#[[Zoisite]]<br />
##[[Tanzanite]]<br />
##[[Thulite]]<br />
#[[Garnet]]<br />
##[[Almandine]]<br />
##[[Andradite]]<br />
###[[Andradite#Demantoid|Demantoid]]<br />
##[[Grossular]]<br />
###[[Grossular#Chrome_grossular|Chrome grossular]]<br />
###[[Grossular#Hessonite|Hessonite]]<br />
###[[Grossular#Hydrogrossular |Hydrogrossular]]<br />
###[[Grossular#Mali|Mali]]<br />
###[[Grossular#Tsavorite|Tsavorite]]<br />
##[[Pyrope]]<br />
##[[Spessartite]]<br />
##[[Uvarovite]]<br />
#[[Diopside]]<br />
##[[Chrome Diopside]]<br />
##[[Tashmarine]]&trade;<br />
#[[Feldspar]]<br />
##[[Amazonite]]<br />
##[[Andesine]]<br />
##[[Labradorite]]<br />
##[[Moonstone]]<br />
##[[Spectrolite]]<br />
##[[Sunstone]]<br />
#[[Spodumene]]<br />
##[[Hiddenite]]<br />
##[[Kunzite]]<br />
#[[Chrysoberyl]]<br />
##[[Alexandrite]]<br />
#[[Spinel]]<br />
#[[Tourmaline]]<br />
#*Species<br />
##[[Chromdravite]]<br />
##[[Dravite]]<br />
##[[Elbaite]]<br />
##[[Liddicoatite]]<br />
##[[Schorl]] <br />
#*Varieties<br />
##[[Achroite]]<br />
##[[Bi-color]]<br />
##[[Indicolite]]<br />
##[[Paraiba]]<br />
##[[Rubellite]]<br />
##[[Siberite]]<br />
##[[Tri-Color]]<br />
##[[Verdelite]]<br />
##[[Watermelon]]<br />
#[[Amber]]<br />
#[[Ammolite]]<br />
#[[Anatase]]<br />
#[[Andalusite]]<br />
#[[Apatite]]<br />
#[[Axinite]]<br />
#[[Azurite]]<br />
#[[Benitoite]]<br />
#[[Bowenite]]<br />
#[[Calcite]]<br />
#[[Charoite]]<br />
#[[Chrysocolla]]<br />
#[[Clinohumite]]<br />
#[[Copal]]<br />
#[[Coral]]<br />
#[[Synthetic cubic zirconia|Cubic zirconia (synthetic)]]<br />
#[[Danburite]]<br />
#[[Datolite]]<br />
#[[Diaspore]]<br />
#[[Dioptase]]<br />
#[[Ekanite]]<br />
#[[Enstatite]]<br />
#[[Fluorite]]<br />
#[[Synthetic forsterite|Forsterite (synthetic)]]<br />
#[[Glass]]<br />
##[[Obsidian]]<br />
##[[Goldstone]]<br />
#[[Hauyne]]<br />
#[[Iolite]]<br />
#[[Jade]]<br />
##[[Jadeite]]<br />
##[[Nephrite]]<br />
#[[Kornerupine]]<br />
#[[Kyanite]]<br />
#[[Lapis Lazuli]]<br />
#[[Larimar]]<br />
#[[Malachite]]<br />
#[[Maw-sit-sit]]<br />
#[[Synthetic moissanite|Moissanite (synthetic)]]<br />
#[[Opal]]<br />
##[[Black Opal]]<br />
##[[Blue Peruvian Opal]]<br />
##[[Boulder Opal]]<br />
##[[Fire Opal]]<br />
#[[Pearl]]<br />
##[[Salt water]]<br />
###[[Akoya pearl]]<br />
###[[Tahitian]]<br />
###[[South Sea]]<br />
###[[Mabé]]<br />
###[[Sea of Cortez pearl]]<br />
###[[Conch Pearl]]<br />
###[[Melo melo pearl]]<br />
###[[Quahog]]<br />
##[[Freshwater pearl]]<br />
###[[Kasumiga pearl]]<br />
###[[Chinese freshwater pearl]]<br />
#[[Pectolite]]<br />
##[[Larimar]]<br />
#[[Peridot]]<br />
#[[Phenakite]]<br />
#[[Poudretteite]]<br />
#[[Rhodocrosite]]<br />
#[[Scapolite]]<br />
#[[Siderite]]<br />
#[[Sodalite]]<br />
##[[Hackmanite]]<br />
#[[Sphalerite]]<br />
#[[Sphene]]<br />
#[[Topaz]]<br />
#[[Turquoise]]<br />
#[[Vesuvianite]]<br />
##[[Idocrase]]<br />
##[[Californite]]<br />
##[[Cyprine]]<br />
#[[Willemite]]<br />
#[[Zincite]]<br />
#[[Zircon]]<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Table_Of_Contents&diff=7510Table Of Contents2007-12-22T08:25:22Z<p>Nick Lombard: </p>
<hr />
<div>In this TOC (Table Of Contents) you will find pages that have been published presented in blue and pages that yet need to be written presented in red. For better navigation, we list the pages in 3 categories:<br />
#Theory - Basic and in-depth mechanisms involved in gemology<br />
#Practical - Descriptions of instruments, techniques and other practical discussions<br />
#Gemstones - Information about the gemstone at hand<br />
<br />
For the neophyte it is best to start in that order as some words and principles introduced in the theory pages will need to be understood first. At the very least, one should learn the theory in the "basic" sections of the pages.<br /><br />
Although gemology is not rocket science, some science and math is involved. We don't believe in the dumbing-down of gemology, so you should be ready and willing to expand your horizons. If you find any of the technical concepts difficult to visualize or grasp, go to the forum (the link is above) and ask. We will help you with it, and at the same time you will help this project become more complete for those who come after you. <br />
<br />
We never said it was going to be easy. But it's a heck of an interesting ride.<br />
<br />
<br />
{| {{toctable}} width="100%"<br />
<br />
!Theory <br />
!Practical<br />
!Gemstones<br />
<br />
|-<br />
<br />
|style="padding-right:5px" valign="top"|<br />
:'''Content'''<br />
#[[Introduction to Gemology]]<br />
##[[Introduction_to_Gemology#Education|Education]]<br />
##[[Glossary of Terms]]<br />
#[[Origins of minerals]]<br />
##[[Origins_of_minerals#Igneous_.28Magmatic.29_rocks|Igneous rocks]]<br />
##[[Origins_of_minerals#Sedimentary_rocks|Sedimentary rocks]]<br />
##[[Origins_of_minerals#Metamorphic_rocks|Metamorphic rocks]]<br />
#[[The Chemistry of Gemstones]]<br />
##[[Isomorphous replacement]]<br />
##[[The Chemical Classification of Gems & Minerals]]<br />
#[[Crystallography]]<br />
##[[Crystal Systems]]<br />
##[[Form]]<br />
##[[Habit]]<br />
##[[Symmetry]]<br />
##[[Twinning]]<br />
#[[Cleavage]]<br />
#[[Cleavage#Parting|Parting]]<br />
#[[Cleavage#Fracture|Fracture]]<br />
#[[Optical properties of gemstones]]<br />
##[[Nature of light]]<br />
###[[Nature_of_light#The_electromagnetic_wave_theory |The electromagnetic wave theory]]<br />
###[[Nature_of_light#The_quantum_theory |The quantum theory]]<br />
###[[Nature_of_light#The_electromagnetic_spectrum |The electromagnetic spectrum]]<br />
##[[Reflection]]<br />
###[[Luster]]<br />
###[[Sheen]]<br />
####[[Sheen#Chatoyancy | Chatoyancy]]<br />
####[[Sheen#Asterism | Asterism]]<br />
####[[Sheen#Iridescence | Iridescence]]<br />
###[[Brilliance | Brilliance (Total Internal Reflection)]]<br />
##[[Polarization]]<br />
##[[Pleochroism]]<br />
##[[Color]]<br />
###[[Color grading]]<br />
###[[Causes of color]]<br />
##[[Refraction]]<br />
###[[Double Refraction]]<br />
##[[Dispersion]]<br />
##[[Diffraction]]<br />
##[[Interference]]<br />
##[[Luminescence]]<br />
###[[Luminescence#Fluorescence | Fluorescence]]<br />
###[[Luminescence#Phosphorescence | Phosphorescence]]<br />
###[[Luminescence#Tenebrescence | Tenebrescence]]<br />
###[[Luminescence#Triboluminescence | Triboluminescence]]<br />
#[[Hardness]]<br />
#[[Specific Gravity]]<br />
#[[Math| Basic math for gemology]]<br />
##[[Math#Cross-multiplication | Cross-multiplication]]<br />
##[[Math#Sine.2C_cosine_and_tangent | Sine, cosine and tangent]]<br />
##[[Math#Degrees.2C_minutes_and_seconds | Degrees, minutes and seconds]]<br />
<br />
| style="padding-right:5px" valign=top|<br />
:'''Content'''<br />
#[[Equipment used to identify gemstones]]<br />
##[[10x Loupe]]<br />
##[[Spectroscope]]<br />
##[[Refractometer]]<br />
##[[Polariscope]]<br />
##[[Dichroscope]]<br />
##[[Immersion cell]]<br />
##[[Color Filters]]<br />
##[[Microscope]]<br />
##[[Hydrostatic Balance]]<br />
##[[Heavy Liquids]]<br />
##[[Hardness#Hardness_pencils|Hardness pencils]]<br />
#[[Inclusions]]<br />
#[[Synthetic gemstones]]<br />
#*Methods<br />
##[[Sublimation]]<br />
##[[Skull crucible]]<br />
##[[Flame fusion]] (Verneuil method)<br />
#*Gemstones<br />
##[[Synthetic forsterite]]<br />
##[[Synthetic moissanite]]<br />
##[[Synthetic cubic zirconia]]<br />
#[[Visual Optics]]<br />
##[[The Hodgkinson Method]]<br />
#[[Video presentations]]<br />
<br />
<br />
:'''Essays'''<br />
#[[essays:adding arrows|Adding arrows]]<br />
<br />
| style="padding-right:5px" valign=top|<br />
:'''Content'''<br />
*[[Alphabetic list by gemstone name]]<br />
#[[Diamond]]<br />
#[[Corundum]]<br />
##[[Ruby]]<br />
##[[Sapphire]]<br />
#[[Beryl]]<br />
##[[Aquamarine]]<br />
##[[Bixbite]]<br />
##[[Emerald]]<br />
###[[Vanadium Beryl]]<br />
##[[Goshenite]]<br />
##[[Green Beryl]]<br />
##[[Heliodor]]<br />
##[[Maxixe]]<br />
##[[Morganite]]<br />
##[[Riesling]]<br />
##[[True Blue]]<br />
##[[Pezzottaite]] (Beryl Group)<br />
#[[Quartz]]<br />
##[[Amethyst]]<br />
##[[Ametrine]]<br />
##[[Citrine]]<br />
##[[Prasiolite]]<br />
##[[Rock Crystal]]<br />
##[[Rose Quartz]]<br />
##[[Smokey Quartz]]<br />
#[[Quartz - Polycrystalline]]<br />
##[[Chalcedony]]<br />
###[[Agate]]<br />
###[[Arkansas stone]]<br />
###[[Bloodstone]]<br />
###[[Carnelian]]<br />
###[[Chrysoprase]]<br />
###[[Jasper]]<br />
###[[Onyx]]<br />
###[[Sard]]<br />
###[[Sardonyx]]<br />
###[[Tigereye]]<br />
#[[Zoisite]]<br />
##[[Tanzanite]]<br />
##[[Thulite]]<br />
#[[Garnet]]<br />
##[[Almandine]]<br />
##[[Andradite]]<br />
###[[Andradite#Demantoid|Demantoid]]<br />
##[[Grossular]]<br />
###[[Grossular#Chrome_grossular|Chrome grossular]]<br />
###[[Grossular#Hessonite|Hessonite]]<br />
###[[Grossular#Hydrogrossular |Hydrogrossular]]<br />
###[[Grossular#Mali|Mali]]<br />
###[[Grossular#Tsavorite|Tsavorite]]<br />
##[[Pyrope]]<br />
##[[Spessartite]]<br />
##[[Uvarovite]]<br />
#[[Diopside]]<br />
##[[Chrome Diopside]]<br />
##[[Tashmarine]]&trade;<br />
#[[Feldspar]]<br />
##[[Amazonite]]<br />
##[[Andesine]]<br />
##[[Labradorite]]<br />
##[[Moonstone]]<br />
##[[Spectrolite]]<br />
##[[Sunstone]]<br />
#[[Spodumene]]<br />
##[[Hiddenite]]<br />
##[[Kunzite]]<br />
#[[Chrysoberyl]]<br />
##[[Alexandrite]]<br />
#[[Spinel]]<br />
#[[Tourmaline]]<br />
#*Species<br />
##[[Chromdravite]]<br />
##[[Dravite]]<br />
##[[Elbaite]]<br />
##[[Liddicoatite]]<br />
##[[Schorl]] <br />
#*Varieties<br />
##[[Achroite]]<br />
##[[Bi-color]]<br />
##[[Indicolite]]<br />
##[[Paraiba]]<br />
##[[Rubellite]]<br />
##[[Siberite]]<br />
##[[Tri-Color]]<br />
##[[Verdelite]]<br />
##[[Watermelon]]<br />
#[[Amber]]<br />
#[[Ammolite]]<br />
#[[Anatase]]<br />
#[[Andalusite]]<br />
#[[Apatite]]<br />
#[[Axinite]]<br />
#[[Azurite]]<br />
#[[Benitoite]]<br />
#[[Bowenite]]<br />
#[[Charoite]]<br />
#[[Chrysocolla]]<br />
#[[Clinohumite]]<br />
#[[Copal]]<br />
#[[Coral]]<br />
#[[Synthetic cubic zirconia|Cubic zirconia (synthetic)]]<br />
#[[Danburite]]<br />
#[[Datolite]]<br />
#[[Diaspore]]<br />
#[[Dioptase]]<br />
#[[Ekanite]]<br />
#[[Enstatite]]<br />
#[[Fluorite]]<br />
#[[Synthetic forsterite|Forsterite (synthetic)]]<br />
#[[Glass]]<br />
##[[Obsidian]]<br />
##[[Goldstone]]<br />
#[[Hauyne]]<br />
#[[Iolite]]<br />
#[[Jade]]<br />
##[[Jadeite]]<br />
##[[Nephrite]]<br />
#[[Kornerupine]]<br />
#[[Kyanite]]<br />
#[[Lapis Lazuli]]<br />
#[[Larimar]]<br />
#[[Malachite]]<br />
#[[Maw-sit-sit]]<br />
#[[Synthetic moissanite|Moissanite (synthetic)]]<br />
#[[Opal]]<br />
##[[Black Opal]]<br />
##[[Blue Peruvian Opal]]<br />
##[[Boulder Opal]]<br />
##[[Fire Opal]]<br />
#[[Pearl]]<br />
##[[Salt water]]<br />
###[[Akoya pearl]]<br />
###[[Tahitian]]<br />
###[[South Sea]]<br />
###[[Mabé]]<br />
###[[Sea of Cortez pearl]]<br />
###[[Conch Pearl]]<br />
###[[Melo melo pearl]]<br />
###[[Quahog]]<br />
##[[Freshwater pearl]]<br />
###[[Kasumiga pearl]]<br />
###[[Chinese freshwater pearl]]<br />
#[[Pectolite]]<br />
##[[Larimar]]<br />
#[[Peridot]]<br />
#[[Phenakite]]<br />
#[[Poudretteite]]<br />
#[[Rhodocrosite]]<br />
#[[Scapolite]]<br />
#[[Siderite]]<br />
#[[Sodalite]]<br />
##[[Hackmanite]]<br />
#[[Sphalerite]]<br />
#[[Sphene]]<br />
#[[Topaz]]<br />
#[[Turquoise]]<br />
#[[Vesuvianite]]<br />
##[[Idocrase]]<br />
##[[Californite]]<br />
##[[Cyprine]]<br />
#[[Willemite]]<br />
#[[Zincite]]<br />
#[[Zircon]]<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Talk:Cleavage&diff=7509Talk:Cleavage2007-12-22T08:19:54Z<p>Nick Lombard: /* Cleavage, parting and fracture */</p>
<hr />
<div>== Cleavage, parting and fracture ==<br />
<br />
I put all 3 on the same page for now until there is more content. --[[User:Doos|Doos]] 08:32, 18 December 2006 (PST)<br />
<br />
<br />
Added a table for Cleavage example stones. Haven't found info on Pinacoidal cleavage or the quality of Calcite cleavage yet. --[[User:Nick_Lombard|nickl]] 02:46, 22 December 2007<br />
<br />
Found Calcite cleavage quality--[[User:Nick_Lombard|nickl]] 15:20, 22 December 2007</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Talk:Cleavage&diff=7508Talk:Cleavage2007-12-22T08:19:40Z<p>Nick Lombard: /* Cleavage, parting and fracture */</p>
<hr />
<div>== Cleavage, parting and fracture ==<br />
<br />
I put all 3 on the same page for now until there is more content. --[[User:Doos|Doos]] 08:32, 18 December 2006 (PST)<br />
<br />
<br />
Added a table for Cleavage example stones. Haven't found info on Pinacoidal cleavage or the quality of Calcite cleavage yet. --[[User:Nick_Lombard|nickl]] 02:46, 22 December 2007<br />
Found Calcite cleavage quality--[[User:Nick_Lombard|nickl]] 15:20, 22 December 2007</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Template:Calcite&diff=7507Template:Calcite2007-12-22T08:13:53Z<p>Nick Lombard: </p>
<hr />
<div>{| align=right width=250px {{table}}<br />
|-<br />
! colspan=2 | Calcite<br />
|-<br />
| Chemical composition || CaCO<sub>3</sub><br />
|-<br />
| Crystal system || Hexagonal(Trigonal)<br />
|-<br />
| Habit || Massive<br />
|-<br />
| Hardness || 3 <br />
|- <br />
| Specific gravity || 2.69 - 2.71<br />
|- <br />
| Optic nature || Uniaxial -<br />
|- <br />
| Refractive Index || 1.486 - 1.658<br />
|- <br />
| Birefringence || 0.172 - 0.19<br />
|-<br />
| Lustre || Vitreous<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Template:Rhodochrosite&diff=7506Template:Rhodochrosite2007-12-22T08:13:31Z<p>Nick Lombard: </p>
<hr />
<div>{| align=right width=250px {{table}}<br />
|-<br />
! colspan=2 | Rhodocrosite<br />
|-<br />
| Chemical composition || MnCO<sub>3</sub> + Fe, Ca<br />
|-<br />
| Crystal system || Hexagonal<br />
|-<br />
| Habit || Rhombohedral<br />
|-<br />
| Colors || pink, red, yellowish, gray, brown<br />
|-<br />
| Hardness || 3.5 - 4 <br />
|- <br />
| Specific gravity || 3.40 - 3.70<br />
|- <br />
| Optic nature || Uniaxial -<br />
|- <br />
| Refractive Index || 1.60 - 1.83<br />
|- <br />
| Birefringence || 0.208 - 0.220<br />
|-<br />
| Lustre || Vitreous to pearly<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Template:Rhodochrosite&diff=7505Template:Rhodochrosite2007-12-22T08:12:11Z<p>Nick Lombard: </p>
<hr />
<div>{| align=right width=250px {{table}}<br />
|-<br />
! colspan=2 | Rhodocrosite<br />
|-<br />
| Chemical composition || MnCO<sub>3</sub> + Fe, Ca<br />
|-<br />
| Crystal system || Hexagonal<br />
|-<br />
| Habit || Rhombohedral<br />
|-<br />
| Colors || pink, red, yellowish, gray, brown<br />
|-<br />
| Hardness || 3.5 - 4 <br />
|- <br />
| Specific gravity || 3.40 - 3.70<br />
|- <br />
| Refractive Index || 1.60 - 1.83<br />
|- <br />
| Birefringence || 0.208 - 0.220 Uniaxial -<br />
|-<br />
| Lustre || Vitreous to pearly<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Template:Calcite&diff=7504Template:Calcite2007-12-22T08:11:34Z<p>Nick Lombard: </p>
<hr />
<div>{| align=right width=250px {{table}}<br />
|-<br />
! colspan=2 | Calcite<br />
|-<br />
| Chemical composition || CaCO<sub>3</sub><br />
|-<br />
| Crystal system || Hexagonal(Trigonal)<br />
|-<br />
| Habit || Massive<br />
|-<br />
| Hardness || 3 <br />
|- <br />
| Specific gravity || 2.69 - 2.71<br />
|- <br />
| Refractive Index || 1.486 - 1.658<br />
|- <br />
| Birefringence || 0.172 - 0.19 Uniaxial negative<br />
|-<br />
| Lustre || Vitreous<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Template:Rhodochrosite&diff=7503Template:Rhodochrosite2007-12-22T08:08:44Z<p>Nick Lombard: </p>
<hr />
<div>{| align=right width=250px {{table}}<br />
|-<br />
! colspan=2 | Rhodocrosite<br />
|-<br />
| Chemical composition || MnCO<sub>3</sub> + Fe, Ca<br />
|-<br />
| Crystal system || Hexagonal<br />
|-<br />
| Habit || Rhombohedral<br />
|-<br />
| Colors || pink, red, yellowish, gray, brown<br />
|-<br />
| Hardness || 3.5 - 4 <br />
|- <br />
| Specific gravity || 3.40 - 3.70<br />
|- <br />
| Refractive Index || 1.60 - 1.83<br />
|- <br />
| Birefringence || 0.208 - 0.220 Uniaxial negative<br />
|-<br />
| Lustre || Vitreous to pearly<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Calcite&diff=7502Calcite2007-12-22T08:00:27Z<p>Nick Lombard: </p>
<hr />
<div>{{calcite}}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Template:Rhodochrosite&diff=7501Template:Rhodochrosite2007-12-22T07:59:13Z<p>Nick Lombard: New template for Rhodocrosite</p>
<hr />
<div>{| align=right width=250px {{table}}<br />
|-<br />
! colspan=2 | Rhodocrosite<br />
|-<br />
| Chemical composition || MnCO<sub>3</sub> + Fe, Ca<br />
|-<br />
| Crystal system || Hexagonal<br />
|-<br />
| Habit || Rhombohedral<br />
|-<br />
| Colors || pink, red, yellowish, gray, brown<br />
|-<br />
| Hardness || 3.5 - 4 <br />
|- <br />
| Specific gravity || 3.40 - 3.60<br />
|- <br />
| Refractive Index || 1.60 - 1.83<br />
|- <br />
| Birefringence || 0.220 Uniaxial negative<br />
|-<br />
| Lustre || Vitreous to pearly<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Rhodocrosite&diff=7500Rhodocrosite2007-12-22T07:51:15Z<p>Nick Lombard: </p>
<hr />
<div>{{rhodocrosite}}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Cleavage&diff=7499Cleavage2007-12-22T07:45:48Z<p>Nick Lombard: /* Cleavage */</p>
<hr />
<div>__forcetoc__<br />
<br />
==Cleavage==<br />
Cleavage is the splitting of a gemstone along the direction of its crystal faces where atoms have weaker bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction. The result of cleavage is a more or less flat plane with often a silky luster.<br /><br />
Cleavage is a reproducable property of a gemstone and can be done at any point of the cleavage direction.<br />
<br />
There are several directions of cleavage.<br />
* Prismatic cleavage<br />
* Basal cleavage<br />
* Pinacoidal cleavage<br />
* Octahedral cleavage <br />
* Rhombohedral cleavage<br />
<br />
The quality of cleavage is expressed with a few simple phrases.<br />
* Perfect<br />
* Good<br />
* Fair<br />
* Poor<br />
* None<br />
<br />
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]<br />
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]<br />
<br clear=all><br />
Stones and their cleavage directions:<br />
<br />
{| {{table}} width="50%"<br />
|-<br />
! Cleavage || Directions || Stones || Quality<br />
|-<br />
| align=center| Basal <br />
| align=center| 1 <br />
| align=center| [[Topaz]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Beryl]]<br />
| align=center| Imperfect<br />
|-<br />
| align=center| Prismatic <br />
| align=center| 2 <br />
| align=center| [[Peridot]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Spodumene]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Chrysoberyl]]<br />
| align=center| Weak to Moderate<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Diopside]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Cubic <br />
| align=center| 3 <br />
| align=center| [[Halite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Rhombohedral <br />
| align=center| 3 <br />
| align=center| [[Calcite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Rhodocrosite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Octhahedral <br />
| align=center| 4 <br />
| align=center| [[Fluorite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Diamond]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Dodecahedral <br />
| align=center| 6<br />
| align=center| [[Sphalerite]]<br />
| align=center| Perfect<br />
|}<br />
<br clear=all><br />
<br />
==Parting==<br />
<br />
Parting is the splitting of a gemstone along twinning or pressure planes.<br /><br />
Although this is similar to cleavage, parting can only be done along certain, well defined, planes of weakness and it is not reproducable like cleavage. Usually these parting planes are created during growth of a crystal when pressure was applied to the crystal causing it to (partially) break or fracture. Later overgrowth then heals the fracture, leaving a weak area inside.<br />
<br />
One of the most profound examples of parting is mica which concists of many very thin layers that can be easily parted with the fingernail. It is this mineral that is traditionally used for [[Polariscope#Quarter_wave_plates|quarter wave plates]].<br />
==Fracture==<br />
<br />
Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object along a direction other than then the direction of cleavage or parting. The most common type of fracture is termed "conchoidal" (shell-like).<br /><br />
<br />
The types of fracture are:<br />
* conchoidal<br />
* uneven<br />
* even<br />
* splintery<br />
* granular<br />
<br />
<br />
==Sources==<br />
<br />
* ''Gemmology'' (2005) - Peter Read<br />
<br />
==External links==<br />
<br />
* [http://www.galleries.com/minerals/property/parting.htm Parting]<br />
* [http://www.galleries.com/minerals/property/cleavage.htm Cleavage]</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Cleavage&diff=7498Cleavage2007-12-22T07:37:08Z<p>Nick Lombard: /* Cleavage */</p>
<hr />
<div>__forcetoc__<br />
<br />
==Cleavage==<br />
Cleavage is the splitting of a gemstone along the direction of its crystal faces where atoms have weaker bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction. The result of cleavage is a more or less flat plane with often a silky luster.<br /><br />
Cleavage is a reproducable property of a gemstone and can be done at any point of the cleavage direction.<br />
<br />
There are several directions of cleavage.<br />
* Prismatic cleavage<br />
* Basal cleavage<br />
* Pinacoidal cleavage<br />
* Octahedral cleavage <br />
* Rhombohedral cleavage<br />
<br />
The quality of cleavage is expressed with a few simple phrases.<br />
* Perfect<br />
* Good<br />
* Fair<br />
* Poor<br />
* None<br />
<br />
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]<br />
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]<br />
<br clear=all><br />
Stones and their cleavage directions:<br />
<br />
{| {{table}} width="50%"<br />
|-<br />
! Cleavage || Directions || Stones || Quality<br />
|-<br />
| align=center| Basal <br />
| align=center| 1 <br />
| align=center| [[Topaz]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Beryl]]<br />
| align=center| Imperfect<br />
|-<br />
| align=center| Prismatic <br />
| align=center| 2 <br />
| align=center| [[Peridot]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Spodumene]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Chrysoberyl]]<br />
| align=center| Weak to Moderate<br />
|-<br />
| align=center| Cubic <br />
| align=center| 3 <br />
| align=center| [[Halite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Rhombohedral <br />
| align=center| 3 <br />
| align=center| [[Calcite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Octhahedral <br />
| align=center| 4 <br />
| align=center| [[Fluorite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Diamond]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Dodecahedral <br />
| align=center| 6<br />
| align=center| [[Sphalerite]]<br />
| align=center| Perfect<br />
|}<br />
<br clear=all><br />
<br />
==Parting==<br />
<br />
Parting is the splitting of a gemstone along twinning or pressure planes.<br /><br />
Although this is similar to cleavage, parting can only be done along certain, well defined, planes of weakness and it is not reproducable like cleavage. Usually these parting planes are created during growth of a crystal when pressure was applied to the crystal causing it to (partially) break or fracture. Later overgrowth then heals the fracture, leaving a weak area inside.<br />
<br />
One of the most profound examples of parting is mica which concists of many very thin layers that can be easily parted with the fingernail. It is this mineral that is traditionally used for [[Polariscope#Quarter_wave_plates|quarter wave plates]].<br />
==Fracture==<br />
<br />
Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object along a direction other than then the direction of cleavage or parting. The most common type of fracture is termed "conchoidal" (shell-like).<br /><br />
<br />
The types of fracture are:<br />
* conchoidal<br />
* uneven<br />
* even<br />
* splintery<br />
* granular<br />
<br />
<br />
==Sources==<br />
<br />
* ''Gemmology'' (2005) - Peter Read<br />
<br />
==External links==<br />
<br />
* [http://www.galleries.com/minerals/property/parting.htm Parting]<br />
* [http://www.galleries.com/minerals/property/cleavage.htm Cleavage]</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Table_Of_Contents&diff=7497Table Of Contents2007-12-21T21:20:35Z<p>Nick Lombard: Added Malachite to the list - still needs to be completed</p>
<hr />
<div>In this TOC (Table Of Contents) you will find pages that have been published presented in blue and pages that yet need to be written presented in red. For better navigation, we list the pages in 3 categories:<br />
#Theory - Basic and in-depth mechanisms involved in gemology<br />
#Practical - Descriptions of instruments, techniques and other practical discussions<br />
#Gemstones - Information about the gemstone at hand<br />
<br />
For the neophyte it is best to start in that order as some words and principles introduced in the theory pages will need to be understood first. At the very least, one should learn the theory in the "basic" sections of the pages.<br /><br />
Although gemology is not rocket science, some science and math is involved. We don't believe in the dumbing-down of gemology, so you should be ready and willing to expand your horizons. If you find any of the technical concepts difficult to visualize or grasp, go to the forum (the link is above) and ask. We will help you with it, and at the same time you will help this project become more complete for those who come after you. <br />
<br />
We never said it was going to be easy. But it's a heck of an interesting ride.<br />
<br />
<br />
{| {{toctable}} width="100%"<br />
<br />
!Theory <br />
!Practical<br />
!Gemstones<br />
<br />
|-<br />
<br />
|style="padding-right:5px" valign="top"|<br />
:'''Content'''<br />
#[[Introduction to Gemology]]<br />
##[[Introduction_to_Gemology#Education|Education]]<br />
##[[Glossary of Terms]]<br />
#[[Origins of minerals]]<br />
##[[Origins_of_minerals#Igneous_.28Magmatic.29_rocks|Igneous rocks]]<br />
##[[Origins_of_minerals#Sedimentary_rocks|Sedimentary rocks]]<br />
##[[Origins_of_minerals#Metamorphic_rocks|Metamorphic rocks]]<br />
#[[The Chemistry of Gemstones]]<br />
##[[Isomorphous replacement]]<br />
##[[The Chemical Classification of Gems & Minerals]]<br />
#[[Crystallography]]<br />
##[[Crystal Systems]]<br />
##[[Form]]<br />
##[[Habit]]<br />
##[[Symmetry]]<br />
##[[Twinning]]<br />
#[[Cleavage]]<br />
#[[Cleavage#Parting|Parting]]<br />
#[[Cleavage#Fracture|Fracture]]<br />
#[[Optical properties of gemstones]]<br />
##[[Nature of light]]<br />
###[[Nature_of_light#The_electromagnetic_wave_theory |The electromagnetic wave theory]]<br />
###[[Nature_of_light#The_quantum_theory |The quantum theory]]<br />
###[[Nature_of_light#The_electromagnetic_spectrum |The electromagnetic spectrum]]<br />
##[[Reflection]]<br />
###[[Luster]]<br />
###[[Sheen]]<br />
####[[Sheen#Chatoyancy | Chatoyancy]]<br />
####[[Sheen#Asterism | Asterism]]<br />
####[[Sheen#Iridescence | Iridescence]]<br />
###[[Brilliance | Brilliance (Total Internal Reflection)]]<br />
##[[Polarization]]<br />
##[[Pleochroism]]<br />
##[[Color]]<br />
###[[Color grading]]<br />
###[[Causes of color]]<br />
##[[Refraction]]<br />
###[[Double Refraction]]<br />
##[[Dispersion]]<br />
##[[Diffraction]]<br />
##[[Interference]]<br />
##[[Luminescence]]<br />
###[[Luminescence#Fluorescence | Fluorescence]]<br />
###[[Luminescence#Phosphorescence | Phosphorescence]]<br />
###[[Luminescence#Tenebrescence | Tenebrescence]]<br />
###[[Luminescence#Triboluminescence | Triboluminescence]]<br />
#[[Hardness]]<br />
#[[Specific Gravity]]<br />
#[[Math| Basic math for gemology]]<br />
##[[Math#Cross-multiplication | Cross-multiplication]]<br />
##[[Math#Sine.2C_cosine_and_tangent | Sine, cosine and tangent]]<br />
##[[Math#Degrees.2C_minutes_and_seconds | Degrees, minutes and seconds]]<br />
<br />
| style="padding-right:5px" valign=top|<br />
:'''Content'''<br />
#[[Equipment used to identify gemstones]]<br />
##[[10x Loupe]]<br />
##[[Spectroscope]]<br />
##[[Refractometer]]<br />
##[[Polariscope]]<br />
##[[Dichroscope]]<br />
##[[Immersion cell]]<br />
##[[Color Filters]]<br />
##[[Microscope]]<br />
##[[Hydrostatic Balance]]<br />
##[[Heavy Liquids]]<br />
##[[Hardness#Hardness_pencils|Hardness pencils]]<br />
#[[Inclusions]]<br />
#[[Synthetic gemstones]]<br />
#*Methods<br />
##[[Sublimation]]<br />
##[[Skull crucible]]<br />
##[[Flame fusion]] (Verneuil method)<br />
#*Gemstones<br />
##[[Synthetic forsterite]]<br />
##[[Synthetic moissanite]]<br />
##[[Synthetic cubic zirconia]]<br />
#[[Visual Optics]]<br />
##[[The Hodgkinson Method]]<br />
#[[Video presentations]]<br />
<br />
<br />
:'''Essays'''<br />
#[[essays:adding arrows|Adding arrows]]<br />
<br />
| style="padding-right:5px" valign=top|<br />
:'''Content'''<br />
*[[Alphabetic list by gemstone name]]<br />
#[[Diamond]]<br />
#[[Corundum]]<br />
##[[Ruby]]<br />
##[[Sapphire]]<br />
#[[Beryl]]<br />
##[[Aquamarine]]<br />
##[[Bixbite]]<br />
##[[Emerald]]<br />
###[[Vanadium Beryl]]<br />
##[[Goshenite]]<br />
##[[Green Beryl]]<br />
##[[Heliodor]]<br />
##[[Maxixe]]<br />
##[[Morganite]]<br />
##[[Riesling]]<br />
##[[True Blue]]<br />
##[[Pezzottaite]] (Beryl Group)<br />
#[[Quartz]]<br />
##[[Amethyst]]<br />
##[[Ametrine]]<br />
##[[Citrine]]<br />
##[[Prasiolite]]<br />
##[[Rock Crystal]]<br />
##[[Rose Quartz]]<br />
##[[Smokey Quartz]]<br />
#[[Quartz - Polycrystalline]]<br />
##[[Chalcedony]]<br />
###[[Agate]]<br />
###[[Arkansas stone]]<br />
###[[Bloodstone]]<br />
###[[Carnelian]]<br />
###[[Chrysoprase]]<br />
###[[Jasper]]<br />
###[[Onyx]]<br />
###[[Sard]]<br />
###[[Sardonyx]]<br />
###[[Tigereye]]<br />
#[[Zoisite]]<br />
##[[Tanzanite]]<br />
##[[Thulite]]<br />
#[[Garnet]]<br />
##[[Almandine]]<br />
##[[Andradite]]<br />
###[[Andradite#Demantoid|Demantoid]]<br />
##[[Grossular]]<br />
###[[Grossular#Chrome_grossular|Chrome grossular]]<br />
###[[Grossular#Hessonite|Hessonite]]<br />
###[[Grossular#Hydrogrossular |Hydrogrossular]]<br />
###[[Grossular#Mali|Mali]]<br />
###[[Grossular#Tsavorite|Tsavorite]]<br />
##[[Pyrope]]<br />
##[[Spessartite]]<br />
##[[Uvarovite]]<br />
#[[Diopside]]<br />
##[[Chrome Diopside]]<br />
##[[Tashmarine]]&trade;<br />
#[[Feldspar]]<br />
##[[Amazonite]]<br />
##[[Andesine]]<br />
##[[Labradorite]]<br />
##[[Moonstone]]<br />
##[[Spectrolite]]<br />
##[[Sunstone]]<br />
#[[Spodumene]]<br />
##[[Hiddenite]]<br />
##[[Kunzite]]<br />
#[[Chrysoberyl]]<br />
##[[Alexandrite]]<br />
#[[Spinel]]<br />
#[[Tourmaline]]<br />
#*Species<br />
##[[Chromdravite]]<br />
##[[Dravite]]<br />
##[[Elbaite]]<br />
##[[Liddicoatite]]<br />
##[[Schorl]] <br />
#*Varieties<br />
##[[Achroite]]<br />
##[[Bi-color]]<br />
##[[Indicolite]]<br />
##[[Paraiba]]<br />
##[[Rubellite]]<br />
##[[Siberite]]<br />
##[[Tri-Color]]<br />
##[[Verdelite]]<br />
##[[Watermelon]]<br />
#[[Amber]]<br />
#[[Ammolite]]<br />
#[[Anatase]]<br />
#[[Andalusite]]<br />
#[[Apatite]]<br />
#[[Axinite]]<br />
#[[Azurite]]<br />
#[[Benitoite]]<br />
#[[Bowenite]]<br />
#[[Charoite]]<br />
#[[Chrysocolla]]<br />
#[[Clinohumite]]<br />
#[[Copal]]<br />
#[[Coral]]<br />
#[[Synthetic cubic zirconia|Cubic zirconia (synthetic)]]<br />
#[[Danburite]]<br />
#[[Datolite]]<br />
#[[Diaspore]]<br />
#[[Dioptase]]<br />
#[[Ekanite]]<br />
#[[Enstatite]]<br />
#[[Fluorite]]<br />
#[[Synthetic forsterite|Forsterite (synthetic)]]<br />
#[[Glass]]<br />
##[[Obsidian]]<br />
##[[Goldstone]]<br />
#[[Hauyne]]<br />
#[[Iolite]]<br />
#[[Jade]]<br />
##[[Jadeite]]<br />
##[[Nephrite]]<br />
#[[Kornerupine]]<br />
#[[Kyanite]]<br />
#[[Lapis Lazuli]]<br />
#[[Larimar]]<br />
#[[Malachite]]<br />
#[[Maw-sit-sit]]<br />
#[[Synthetic moissanite|Moissanite (synthetic)]]<br />
#[[Opal]]<br />
##[[Black Opal]]<br />
##[[Blue Peruvian Opal]]<br />
##[[Boulder Opal]]<br />
##[[Fire Opal]]<br />
#[[Pearl]]<br />
##[[Salt water]]<br />
###[[Akoya pearl]]<br />
###[[Tahitian]]<br />
###[[South Sea]]<br />
###[[Mabé]]<br />
###[[Sea of Cortez pearl]]<br />
###[[Conch Pearl]]<br />
###[[Melo melo pearl]]<br />
###[[Quahog]]<br />
##[[Freshwater pearl]]<br />
###[[Kasumiga pearl]]<br />
###[[Chinese freshwater pearl]]<br />
#[[Pectolite]]<br />
##[[Larimar]]<br />
#[[Peridot]]<br />
#[[Phenakite]]<br />
#[[Poudretteite]]<br />
#[[Scapolite]]<br />
#[[Siderite]]<br />
#[[Sodalite]]<br />
##[[Hackmanite]]<br />
#[[Sphalerite]]<br />
#[[Sphene]]<br />
#[[Topaz]]<br />
#[[Turquoise]]<br />
#[[Vesuvianite]]<br />
##[[Idocrase]]<br />
##[[Californite]]<br />
##[[Cyprine]]<br />
#[[Willemite]]<br />
#[[Zincite]]<br />
#[[Zircon]]<br />
|}</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Lapis_Lazuli&diff=7496Lapis Lazuli2007-12-21T21:01:42Z<p>Nick Lombard: Added Enhancements</p>
<hr />
<div>{{Lapis_Lazuli}}<br />
[[Image:Lapis-pyrite.JPG|left|framed|Lapis Lazuli with Pyrite inclusions]]<br clear="left" /><br />
==Enhancements==<br />
<br />
Common enhancements to lapis lazuli:<br />
<br />
* Fracture filling - wax (with dye or withou) - conceal cracks and fractures and to improve luster<br />
* Dye - color staining - to produce evenly colored material</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Jadeite&diff=7495Jadeite2007-12-21T20:57:28Z<p>Nick Lombard: /* Enhancements */</p>
<hr />
<div>{{jadeite}}<br />
==Enhancements==<br />
<br />
Common enhancements to jadeite:<br />
<br />
* Fracture filling - wax - conceal cracks and fractures<br />
* Coatings - wax - to improve luster<br />
* Staining - color improvement through dyes<br />
* Bleaching - removes stains <br />
* Polymer impregnation - improves luster and to stabilize piece after bleaching</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Jadeite&diff=7494Jadeite2007-12-21T20:56:35Z<p>Nick Lombard: Added Enhancements</p>
<hr />
<div>{{jadeite}}<br />
==Enhancements==<br />
<br />
Common enhancements to jadeite:<br />
<br />
* Fracture filling - wax - conceal cracks and fractures<br />
* Coatings - wax - to improve luster<br />
* Staining - color improvement through dyes<br />
* Bleaching - removes stains <br />
* Polymer impregnation - improves luster and conceals bleaching</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Nephrite&diff=7493Nephrite2007-12-21T20:50:05Z<p>Nick Lombard: Added Enhancements</p>
<hr />
<div>{{nephrite}}<br />
==Enhancements==<br />
<br />
Common enhancements to nephrite:<br />
<br />
* Fracture filling - wax - conceal cracks and fractures<br />
* Coatings - wax - to improve luster</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Sapphire&diff=7492Sapphire2007-12-21T20:41:06Z<p>Nick Lombard: </p>
<hr />
<div>{{sapphire}}<br />
[[Image:Ceylon.JPG|left|thumb|240px|Cornflower Ceylon sapphire]]<br />
<br clear="left" /><br />
<br />
{{images}}<br />
<br />
Sapphire (a [[corundum]] variety) is an aluminum oxide occurring in every color of the rainbow. It is a stone of great hardness and durability. It can also have phenomenal characteristics like asterism (star sapphire) and color changing (like alexandrite). The color changing varieties are mesmerizing, having the ability to change color depending on whether they are viewed in daylight or incandescent light.<br />
<br />
The name is derived from the Greek word "sappheiros" meaning "blue". The history of sapphire dates back to at least the 7th century BC, when they were used by the Etruscans. The sapphires used by the Etruscans, Greeks and Romans were imported from India (what is now Sri Lanka). Sapphires were reputed to protect kings from harm and envy. In the 13th century, it was written that sapphires had the power to protect against poverty, to make a stupid man wise and an irritable man good-tempered.<br />
<br />
==Diagnostics==<br />
<br />
===Color===<br />
<br />
Sapphire occurs in many colors ranging from colorless to black. When a [[corundum]] variety is termed "sapphire" it indicates the blue variety. Any other color (except red, which is named [[ruby]]) will have a prefix before "sapphire", such as "yellow sapphire".<br />
<br />
Causes of color:<br />
<br />
* sapphire (blue) - charge transfer between Ti and Fe.<br />
<br />
===Diaphaneity===<br />
<br />
Translucent to opaque<br />
<br />
===Refractometer===<br />
<br />
Sapphire has a refractive index range between n<sub>ω</sub> = 1.767-1.772 and n<sub>ε</sub> = 1.759-1.763, with a maximum birefringence of 0.009.<br /><br />
Optic sign is negative like most, naturally occuring, uniaxial gemstones.<br />
<br />
===Specific gravity===<br />
<br />
The specific gravity of sapphire is between 3.98 and 4.02 (mean = 4).<br /><br />
It will sink is all common used heavy liquids.<br />
<br />
===Spectrum===<br />
[[Image:saph_spectrum.gif|framed|right| Spectrum of blue, green and Australian yellow sapphire (high iron content).]]<br />
<br />
Natural blue, green and yellow sapphires with a high iron content may show the typical "450 complex" as seen in this image. The clear lines at 450 and 460nm (less sharp than the 450nm line) will be accomanied with a third (sometimes faint) line at 470nm. Due to partial absorption of wavelengths between these 450 and 460nm lines, this whole section may blend together with "smudges" between the lines.<br /><br />
With lesser iron content only the 450nm line may be observed in natural blue and yellow sapphire. Although this same 450nm line can also be observed in some blue flame fusion (Verneuil) synthetic sapphire, the "450 complex" has not been reported for synthetic sapphire.<br />
<br clear="left" /><br />
<br />
===Polariscope===<br />
<br />
Most natural sapphires are cut with the table almost perpendicular to the optic axis and an uniaxial interference figure should be easily found. Some synthetics (Verneuil type) are cut with the table parallel to the optic axis and the interference figure will be hard to find on the girdle.<br /><br />
Finding an interference figure on the table is not diagnostic.<br />
<br />
==Phenomena==<br />
<br />
====Asterism====<br />
[[Image:12raystar1.jpg|left|framed|12 pointed star sapphire <br /> Photo courtesy of <br />Wild Fish Gems]]<br />
<br />
<br />
Sapphire may show 6 pointed or 12 pointed stars.<br /><br />
The 6 pointed rays are from reflections on rutile needles that form in directions parallel to the 2nd order prism. 12 pointed rays (mostly from Thailand) form from reflections on rutile needles (2nd order prism) and from reflections of hematite-ilmenite needles that lie in the planes parallel to the 1st order prism.<br />
<br clear="left" /><br />
<br />
====Color change====<br />
[[Image:CCSapp.gif|thumb|left|250px|Under daylight<br>Photo courtesy of The Gem Trader]]<br />
[[Image:CCSapp1.gif|thumb|left|250px|Under incandescent light<br>Photo courtesy of The Gem Trader]]<br />
<br clear="left" /><br />
<br />
====Cat's-eyes====<br />
====Trapiche====<br />
<br />
[[Image:Trapichesapphirepair1am4.jpg|thumb|left|250px|Trapiche sapphires<br />Photo courtesy of Chaman Golecha]]<br />
<br clear="all" /><br />
<br />
==Synthetics==<br />
<br />
====Flame fusion (Verneuil)====<br />
<br />
Color change flame fusion sapphire will have a characteristic absorption spectrum with a fuzzy band in the yellow and a diagnostic line at 475nm (in the blue). In some rare cases this 475 line may be seen in natural sapphire.<br /><br />
Curved growth lines are usually seen.<br />
<br />
====Other synthesizing methods====<br />
<br />
* Flux melt (Chatham, Ramaura)<br />
* Czochralski pulling process<br />
* Float zone method<br />
<br />
==Inclusion Images==<br />
====Un-heated Sapphires====<br />
<br />
[[image:Distorted_guest_crystal_in_untreated_Burmese_pink_sapphire.jpg|thumb|left|240px|Distorted guest crystal (possibly calcite) in an un-treated Burmese pink sapphire.<br>Photo courtesy of Apsara.co.uk]]<br />
[[image:Silk_&_guest_crystals_in_un-heated_Burmese_pink_sapphire.jpg|thumb|left|240px|Silk and guest crystals in an un-treated Burmese pink sapphire.<br>Photo courtesy of Apsara.co.uk]] <br />
[[image:Unusual_cluster_of_rutile_silk_in_un-treated_Madagascan_pink_sapphire..jpg|thumb|left|240px|Unusual cluster of rutile silk in an un-treated Madagascan pink sapphire.<br>Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
<br />
[[image:Calcite_guest_crystal_in_un-heated_Madagascan_pink_sapphire.jpg|thumb|left|240px|Calcite guest crystal in an un-treated Madagascan pink sapphire.<br>Photo courtesy of Apsara.co.uk]]<br />
[[image:Guest_crystals_in_Sri_Lankan_blue_star_sapphire.jpg|thumb|left|240px|Guest crystals in an un-treated Sri Lankan blue star sapphire. Fine rutile silk can be faintly seen in the background.<br>Photo courtesy of Apsara.co.uk]] <br />
[[image:A_multitude_of_guest_crystals_in_un-treated_Burmese_blue_sapphire.jpg|thumb|left|240px|A multitude of guest crystals in an un-treated Burmese blue star sapphire. <br>Photo courtesy of Apsara.co.uk]]<br />
<br clear="left" /><br />
<br />
[[image:Calcite_guest_crystals_in_un-treated_Burmese_blue_sapphire.jpg|thumb|left|240px|Calcite guest crystals in an un-treated Burmese blue sapphire.<br>Photo courtesy of Apsara.co.uk]]<br />
[[image:Liquid_fingerprint_inclusion_in_un-treated_Burmese_blue_sapphire_1.jpg|thumb|left|240px|Liquid fingerprint inclusion in an un-treated Burmese blue sapphire.<br>Photo courtesy of Apsara.co.uk]]<br />
[[image:Liquid_fingerprint_inclusion_in_un-treated_Burmese_blue_sapphire_2.jpg|thumb|left|240px|Liquid fingerprint inclusion in an un-treated Burmese blue sapphire.<br>Photo courtesy of Apsara.co.uk]]<br />
<br clear="left" /><br />
<br />
[[image:Liquid_fingerprints%2C_guest_crystals_and_two-phase_inclusions_in_un-treated_Burmese_blue_sapphire.jpg|thumb|left|240px|Liquid fingerprints, guest crystals and two phase inclusions in an un-treated Burmese blue sapphire.<br>Photo courtesy of Apsara.co.uk]]<br />
[[image:Rounded_guest_crystals_%28possibly_calcite%29_in_un-treated_Burmese_blue_sapphire.jpg|thumb|left|240px|Rounded guest crystals, possibly calcite, in an un-treated Burmese blue sapphire.<br>Photo courtesy of Apsara.co.uk]]<br />
[[image:Un-dissolved_rutile_silk_in_un-treated_Sri_Lankan_blue_sapphire.jpg|thumb|left|240px|Un-dissolved rutile silk in an un-treated Sri Lankan blue sapphire. Iridescent colours can be seen when this inclusion is viewed using a fibre optic light.<br>Photo courtesy of Apsara.co.uk]]<br />
<br clear="left" /><br />
<br />
====Heated Sapphires====<br />
<br />
[[image:Microscopic_particle_inclusions_with_straight_colour_banding_in_heat-treated_Thai_blue_sapphire.jpg|thumb|left|240px|Microscopic particle inclusions with straight colour banding in a heat treated Thai blue sapphire. The particles give the stone a sleepy or hazy appearance which is common to sapphires from Kanchanaburi, Thailand.<br>Photo courtesy of Apsara.co.uk]]<br />
<br clear="left" /><br />
<br />
<br />
====Beryllium-Treated Sapphires====<br />
<br />
[[image:Dendritic_inclusion_with_cotton_wool_type_inclusions_in_beryllium-treated_sapphire.jpg|thumb|left|240px|Dendritic inclusion with 'cotton wool' type inclusions in beryllium-treated sapphire.<br>Photo courtesy of Apsara.co.uk]]<br />
[[image:Liquid_tubular_channel_inclusions_in_breyllium-treated_sapphire.jpg|thumb|left|240px|Liquid tubular channel inclusions in beryllium-treated sapphire.<br>Photo courtesy of Apsara.co.uk]] <br />
[[image:Wheat-like_feather_inclusion_in_beryllium-treated_sapphire.jpg|thumb|left|240px|Wheat-like feather inclusion in beryllium-treated sapphire. <br>Photo courtesy of Apsara.co.uk]]<br />
<br clear="left" /><br />
<br />
[[image:A_cross-sectioned_slice_of_beryllium-treated_sapphire.jpg|thumb|left|240px|A cross-sectioned slice through a beryllium-treated sapphire. The orange colour rim is clearly visible around the pink core.<br>Photo courtesy of Apsara.co.uk]]<br />
<br clear="left" /><br />
<br />
==Occurence==<br />
Kashmir, Burma, Sri Lanka, Madagascar, Australia, China, Montana USA, Thailand<br />
<br />
==Enhancements==<br />
<br />
Common enhancements to sapphire varieties:<br />
<br />
* Fracture filling - oil, wax or plastic (with dye or without)<br />
* Lead glass filling - removes crack increases weight<br />
* Diffusion treated - heating causing layer on cut stones - enhance color or produce asterism <br />
* Heat treatment - improves or even changes the color, reduces silk and other impurities<br />
* Irradiation - change colorless stones to yellow - color unstable<br />
<br />
<br />
==Sources==<br />
<br />
* ''A students' guide to spectroscopy'' (2003) - Colin H. Winter<br />
* ''Ruby & Sapphire'' (1997) - Richard W. Hughes ISBN 0964509768<br />
<br />
==External links==<br />
<br />
* [http://www.gaaj-zenhokyo.co.jp/researchroom/corundum/heat-treatment_01en.html Identification of heated / unheated status on ruby and sapphire]</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Ruby&diff=7491Ruby2007-12-21T20:38:01Z<p>Nick Lombard: /* Enhancements */</p>
<hr />
<div>{{Ruby}}<br />
[[image:7137_d.jpg|thumb|left|240px|3.30 ct heated Mong Hsu ruby<br />Photo by Jeff Scovil<br />Courtesy of R.W. Wise Goldsmiths]]<br />
Ruby is the red variety of the mineral corundum. When corundum occurs in any other color it is referred to as a sapphire. Rubies are mined primarily in Burma, Madagascar, India and Eastern Africa. More important than the gem's locality of origin is the actual color and clarity of the stone. Rubies that are the most valuable will be pure red in color, without any modifying tones of violet, orange or brown and are transparent in clarity. A fine ruby still commands the highest price of any stone in the world!<br />
<br />
<!-- [[Image:ruby.jpg|left|framed|Untreated 2.7 carat Ruby courtesy of Wild Fish Gems]] --><br />
The brilliant red color of the ruby has supported many tales. One is that rubies store vast quantities of heat and when placed in water, they will cause the water to boil. Obviously this is an exaggeration, but I know some that swear if you hold a ruby in your left hand, you'll feel bursts of heat. I'm a bit skeptical, so please let me know if you experience this phenomenon. Ruby, none the less, is a powerful stone and has long been considered a magnet for prosperity, attracting abundance both materially and spiritually. <br clear="left" /><br />
<br />
The word ruby is derived from the Latin "rubeus", meaning "red".<br />
<br />
==Diagnostics==<br />
<br />
===Spectrum===<br />
<br />
[[Image:ruby.gif|framed|left| Spectrum of ruby: both natural and synthetic.]]<br clear="left" /><br />
<br />
==Phenomena==<br />
<br />
* Asterism<br />
* Chatoyancy<br />
* Trapiche<br />
<br />
==Occurrence==<br />
The most famous source of fine rubies is Burma, now known as Myanmar. The ruby mines of Myanmar are older than recorded history; Stone Age and Bronze Age mining tools have been found in the mining area of Mogok. Rubies from the legendary mines in Mogok often have a pure red color, which has been described as "pigeon's-blood" although that term is more fanciful than an actual practical standard in the trade today. Myanmar also produces intense pinkish red rubies which are almost electric in color. Many of the rubies from Burma have a strong fluorescence when exposed to ultraviolet rays like those in sunlight.<br />
<br />
==Inclusion images==<br />
<br />
[[image:Apatite In Untreated Mogok Ruby.jpg|thumb|left|240px|Apatite in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Apatite_In_Untreated_Mogok_Ruby_-_2.jpg|thumb|left|240px|Apatite in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Calcite_In_Untreated_Mogok_Ruby.jpg|thumb|left|240px|Distorted calcite guest crystals in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br clear="left" /><br />
<br />
[[image:Rutile_silk_in_untreated_Mogok_ruby.jpg|thumb|left|240px|Rutile silk in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Heat-treated_Mong_Hsu_ruby_-_1.jpg|thumb|left|240px|Heat treated Mong Hsu ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Partially_dissolved_rutile_silk_in_heat-treated_Vietnamese_ruby.jpg|thumb|left|240px|Partially dissolved rutile silk in heat treated Vietnamese ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Rounded_calcite_guest_crystals_with_'treacle'_colour_swirls_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Rounded calcite guest crystals with 'treacle' colour swirls in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Growth_lines,_guest_crystals_and_un-disolved_silk_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Growth lines, guest crystals and un-disolved rutile silk in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:'Treacle'_colour_swirls,_growth_lines_and_guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Treacle colour swirls, growth lines and guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Rounded_calcite_guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Rounded calcite guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Unusual_acicular_guest_crystal_and_small_particle_inclusions_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Unusual acicular guest crystal and small particle inclusions in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Distorted_calcite_guest_crystal_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Distorted calcite guest crystal in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Apatite_and_calcite_guest_crystals_reflecting_within_un-heated_Mogok_ruby.jpg|thumb|left|240px|Apatite and calcite guest crystals reflecting within an un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
<br />
<br clear="all" /><br />
==Enhancements==<br />
<br />
Common enhancements to rubies:<br />
<br />
* Fracture filling - oil, wax or plastic (with dye or without)<br />
* Lead glass filling - removes crack increases weight<br />
* Diffusion treated - heating causing layer on cut stones - enhance color or produce asterism <br />
* Heat treatment - improves or even changes the color, reduces silk and other impurities</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Ruby&diff=7490Ruby2007-12-21T20:37:34Z<p>Nick Lombard: </p>
<hr />
<div>{{Ruby}}<br />
[[image:7137_d.jpg|thumb|left|240px|3.30 ct heated Mong Hsu ruby<br />Photo by Jeff Scovil<br />Courtesy of R.W. Wise Goldsmiths]]<br />
Ruby is the red variety of the mineral corundum. When corundum occurs in any other color it is referred to as a sapphire. Rubies are mined primarily in Burma, Madagascar, India and Eastern Africa. More important than the gem's locality of origin is the actual color and clarity of the stone. Rubies that are the most valuable will be pure red in color, without any modifying tones of violet, orange or brown and are transparent in clarity. A fine ruby still commands the highest price of any stone in the world!<br />
<br />
<!-- [[Image:ruby.jpg|left|framed|Untreated 2.7 carat Ruby courtesy of Wild Fish Gems]] --><br />
The brilliant red color of the ruby has supported many tales. One is that rubies store vast quantities of heat and when placed in water, they will cause the water to boil. Obviously this is an exaggeration, but I know some that swear if you hold a ruby in your left hand, you'll feel bursts of heat. I'm a bit skeptical, so please let me know if you experience this phenomenon. Ruby, none the less, is a powerful stone and has long been considered a magnet for prosperity, attracting abundance both materially and spiritually. <br clear="left" /><br />
<br />
The word ruby is derived from the Latin "rubeus", meaning "red".<br />
<br />
==Diagnostics==<br />
<br />
===Spectrum===<br />
<br />
[[Image:ruby.gif|framed|left| Spectrum of ruby: both natural and synthetic.]]<br clear="left" /><br />
<br />
==Phenomena==<br />
<br />
* Asterism<br />
* Chatoyancy<br />
* Trapiche<br />
<br />
==Occurrence==<br />
The most famous source of fine rubies is Burma, now known as Myanmar. The ruby mines of Myanmar are older than recorded history; Stone Age and Bronze Age mining tools have been found in the mining area of Mogok. Rubies from the legendary mines in Mogok often have a pure red color, which has been described as "pigeon's-blood" although that term is more fanciful than an actual practical standard in the trade today. Myanmar also produces intense pinkish red rubies which are almost electric in color. Many of the rubies from Burma have a strong fluorescence when exposed to ultraviolet rays like those in sunlight.<br />
<br />
==Inclusion images==<br />
<br />
[[image:Apatite In Untreated Mogok Ruby.jpg|thumb|left|240px|Apatite in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Apatite_In_Untreated_Mogok_Ruby_-_2.jpg|thumb|left|240px|Apatite in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Calcite_In_Untreated_Mogok_Ruby.jpg|thumb|left|240px|Distorted calcite guest crystals in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br clear="left" /><br />
<br />
[[image:Rutile_silk_in_untreated_Mogok_ruby.jpg|thumb|left|240px|Rutile silk in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Heat-treated_Mong_Hsu_ruby_-_1.jpg|thumb|left|240px|Heat treated Mong Hsu ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Partially_dissolved_rutile_silk_in_heat-treated_Vietnamese_ruby.jpg|thumb|left|240px|Partially dissolved rutile silk in heat treated Vietnamese ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Rounded_calcite_guest_crystals_with_'treacle'_colour_swirls_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Rounded calcite guest crystals with 'treacle' colour swirls in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Growth_lines,_guest_crystals_and_un-disolved_silk_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Growth lines, guest crystals and un-disolved rutile silk in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:'Treacle'_colour_swirls,_growth_lines_and_guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Treacle colour swirls, growth lines and guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Rounded_calcite_guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Rounded calcite guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Unusual_acicular_guest_crystal_and_small_particle_inclusions_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Unusual acicular guest crystal and small particle inclusions in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Distorted_calcite_guest_crystal_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Distorted calcite guest crystal in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Apatite_and_calcite_guest_crystals_reflecting_within_un-heated_Mogok_ruby.jpg|thumb|left|240px|Apatite and calcite guest crystals reflecting within an un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
<br />
<br clear="all" /><br />
==Enhancements==<br />
<br />
Common enhancements to corundum varieties:<br />
<br />
* Fracture filling - oil, wax or plastic (with dye or without)<br />
* Lead glass filling - removes crack increases weight<br />
* Diffusion treated - heating causing layer on cut stones - enhance color or produce asterism <br />
* Heat treatment - improves or even changes the color, reduces silk and other impurities</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Ruby&diff=7489Ruby2007-12-21T20:36:42Z<p>Nick Lombard: Added Enhancements</p>
<hr />
<div>{{Ruby}}<br />
[[image:7137_d.jpg|thumb|left|240px|3.30 ct heated Mong Hsu ruby<br />Photo by Jeff Scovil<br />Courtesy of R.W. Wise Goldsmiths]]<br />
Ruby is the red variety of the mineral corundum. When corundum occurs in any other color it is referred to as a sapphire. Rubies are mined primarily in Burma, Madagascar, India and Eastern Africa. More important than the gem's locality of origin is the actual color and clarity of the stone. Rubies that are the most valuable will be pure red in color, without any modifying tones of violet, orange or brown and are transparent in clarity. A fine ruby still commands the highest price of any stone in the world!<br />
<br />
<!-- [[Image:ruby.jpg|left|framed|Untreated 2.7 carat Ruby courtesy of Wild Fish Gems]] --><br />
The brilliant red color of the ruby has supported many tales. One is that rubies store vast quantities of heat and when placed in water, they will cause the water to boil. Obviously this is an exaggeration, but I know some that swear if you hold a ruby in your left hand, you'll feel bursts of heat. I'm a bit skeptical, so please let me know if you experience this phenomenon. Ruby, none the less, is a powerful stone and has long been considered a magnet for prosperity, attracting abundance both materially and spiritually. <br clear="left" /><br />
<br />
The word ruby is derived from the Latin "rubeus", meaning "red".<br />
<br />
==Diagnostics==<br />
<br />
===Spectrum===<br />
<br />
[[Image:ruby.gif|framed|left| Spectrum of ruby: both natural and synthetic.]]<br clear="left" /><br />
<br />
==Phenomena==<br />
<br />
* Asterism<br />
* Chatoyancy<br />
* Trapiche<br />
<br />
==Occurrence==<br />
The most famous source of fine rubies is Burma, now known as Myanmar. The ruby mines of Myanmar are older than recorded history; Stone Age and Bronze Age mining tools have been found in the mining area of Mogok. Rubies from the legendary mines in Mogok often have a pure red color, which has been described as "pigeon's-blood" although that term is more fanciful than an actual practical standard in the trade today. Myanmar also produces intense pinkish red rubies which are almost electric in color. Many of the rubies from Burma have a strong fluorescence when exposed to ultraviolet rays like those in sunlight.<br />
<br />
==Inclusion images==<br />
<br />
[[image:Apatite In Untreated Mogok Ruby.jpg|thumb|left|240px|Apatite in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Apatite_In_Untreated_Mogok_Ruby_-_2.jpg|thumb|left|240px|Apatite in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Calcite_In_Untreated_Mogok_Ruby.jpg|thumb|left|240px|Distorted calcite guest crystals in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br clear="left" /><br />
<br />
[[image:Rutile_silk_in_untreated_Mogok_ruby.jpg|thumb|left|240px|Rutile silk in untreated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Heat-treated_Mong_Hsu_ruby_-_1.jpg|thumb|left|240px|Heat treated Mong Hsu ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Partially_dissolved_rutile_silk_in_heat-treated_Vietnamese_ruby.jpg|thumb|left|240px|Partially dissolved rutile silk in heat treated Vietnamese ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Rounded_calcite_guest_crystals_with_'treacle'_colour_swirls_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Rounded calcite guest crystals with 'treacle' colour swirls in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]]<br />
[[image:Growth_lines,_guest_crystals_and_un-disolved_silk_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Growth lines, guest crystals and un-disolved rutile silk in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:'Treacle'_colour_swirls,_growth_lines_and_guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Treacle colour swirls, growth lines and guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Rounded_calcite_guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Rounded calcite guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Unusual_acicular_guest_crystal_and_small_particle_inclusions_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Unusual acicular guest crystal and small particle inclusions in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Distorted_calcite_guest_crystal_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Distorted calcite guest crystal in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br clear="left" /><br />
<br />
[[image:Guest_crystals_in_un-heated_Mogok_ruby.jpg|thumb|left|240px|Guest crystals in un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
[[image:Apatite_and_calcite_guest_crystals_reflecting_within_un-heated_Mogok_ruby.jpg|thumb|left|240px|Apatite and calcite guest crystals reflecting within an un-heated Mogok ruby<br />Photo courtesy of Apsara.co.uk]] <br />
<br />
<br clear="all" /><br />
===Enhancements===<br />
<br />
Common enhancements to corundum varieties:<br />
<br />
* Fracture filling - oil, wax or plastic (with dye or without)<br />
* Lead glass filling - removes crack increases weight<br />
* Diffusion treated - heating causing layer on cut stones - enhance color or produce asterism <br />
* Heat treatment - improves or even changes the color, reduces silk and other impurities<br />
* Irradiation - change colorless stones to yellow - color unstable</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Beryl&diff=7488Beryl2007-12-21T20:19:22Z<p>Nick Lombard: Added Enhancements</p>
<hr />
<div>{{Beryl}}<br />
<br />
Beryl is a beryllium aluminum silicate that occurs in every color of the rainbow. When green, it's usually called [[emerald]] but there exists [[Green_Beryl| green beryl]], which is not entitled to be called emerald because its coloring agent is different. When blue, it's [[aquamarine]] and when pink, [[morganite]]. Yellow is [[heliodor]] and colorless is [[goshenite]].<br /> A rare raspberry red variety found in Utah is called [[bixbite]]. There is a very rare and costly variety termed [[Riesling]] beryl, that can be described as pale green colored with a warm, golden yellow flash. Two unusually dark blue types of beryl have been found as well: [[Maxixe]] beryl and [[True Blue]] Beryl. [[Maxixe]] beryl fades with exposure to light, [[True Blue]] Beryl does not.<br /> Beryl has been used as a physician's tool and for gazing stones since ancient times. Those beliefs persist today. Beryl is metaphysically attributed with the ability to cure a number of intestinal and stomach ills, such as nausea, ulcers, and seasickness.<br />
<br />
<br />
==Characteristics==<br />
<br />
The optical and physical data of beryl can vary between varieties and localities.<br /><br />
Beryl belongs to the beryl group. [[Pezzottaite]] (IMA approved in 2003) is also a member of the beryl group.<br />
<br />
===Genesis===<br />
<br />
Metamorphic rocks in pegmatites<br />
<br />
===Localities===<br />
<br />
Beryl is found in many localities, among them being Brazil, India, Africa, Columbia, Australia and Pakistan.<br />
<br />
===Habit===<br />
<br />
Prismatic with pyramidal and/or pinacoidal terminations.<br />
Often vertically striated.<br />
<br />
===Physical data===<br />
<br />
Mohs hardness: 7.25 - 7.75 (emerald is brittle).<br /><br />
Specific gravity: 2.7 to 2.9, depending on variety.<br />
<br />
===Optical data===<br />
<br />
Refractive index: n<sub>ε</sub> = 1.56 n<sub>ω</sub> = 1.59, depending on variety.<br /><br />
Birefringence: 0.004 to 0.009, depending on variety.<br /><br />
Optical sign: uniaxial negative.<br /><br />
Dispersion: low, 0.014.<br /><br />
Pleochroism: weak to moderate, strong in "True Blue Beryl" and pezzottaite.<br />
<br />
===Diaphaneity===<br />
<br />
Transparent to opaque.<br />
<br />
===Colors===<br />
<br />
All varieties of beryl are allochromatic. Main coloring agents are given below.<br />
<br />
* Green ([[emerald]]), colored by chromium 3<sup>+</sup><br />
* Green ([[Vanadium_Beryl|vanadium beryl]]), colored by vanadium 3<sup>+</sup> - Also known as vanadium emerald<br />
* Green ([[Green_Beryl|green beryl]]), colored by ferric 3<sup>+</sup> and ferrous 2<sup>+</sup> iron<br />
* Green/Yellow ([[Reisling|Reisling beryl]]), unknown coloring agent (most likely iron)<br />
* Blue ([[aquamarine]]), colored by ferrous 2<sup>+</sup> Iron<br />
* Blue ([[Maxixe]]), colored by color centers<br />
* Blue ([[True Blue]]), colored by ferrous 2<sup>+</sup> iron - Trade name for high FeO content aquamarine<br />
* Pink ([[morganite]]), colored by manganese 2<sup>+</sup><br />
* Red ([[bixbite]]), colored by manganese 3<sup>+</sup><br />
* Yellow ([[heliodor]]), colored by ferric 3<sup>+</sup> Iron<br />
* Colorless ([[goshenite]])<br />
<br />
===Enhancements===<br />
<br />
Common enhancements to beryl varieties:<br />
<br />
* Fracture filling ([[emerald]]) - oil, wax or plastic (with dye or without)<br />
* Coatings ([[emerald]]) - non-metallic paint or plastic (usually green)<br />
* Heat treatment - improves or even changes the color</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Cleavage&diff=7487Cleavage2007-12-21T20:06:54Z<p>Nick Lombard: </p>
<hr />
<div>__forcetoc__<br />
<br />
==Cleavage==<br />
Cleavage is the splitting of a gemstone along the direction of its crystal faces where atoms have weaker bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction. The result of cleavage is a more or less flat plane with often a silky luster.<br /><br />
Cleavage is a reproducable property of a gemstone and can be done at any point of the cleavage direction.<br />
<br />
There are several directions of cleavage.<br />
* Prismatic cleavage<br />
* Basal cleavage<br />
* Pinacoidal cleavage<br />
* Octahedral cleavage <br />
* Rhombohedral cleavage<br />
<br />
The quality of cleavage is expressed with a few simple phrases.<br />
* Perfect<br />
* Good<br />
* Fair<br />
* Poor<br />
* None<br />
<br />
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]<br />
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]<br />
<br clear=all><br />
Stones and their cleavage directions:<br />
<br />
{| {{table}} width="50%"<br />
|-<br />
! Cleavage || Directions || Stones || Quality<br />
|-<br />
| align=center| Basal <br />
| align=center| 1 <br />
| align=center| [[Topaz]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Beryl]]<br />
| align=center| Imperfect<br />
|-<br />
| align=center| Prismatic <br />
| align=center| 2 <br />
| align=center| [[Peridot]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Spodumene]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Cubic <br />
| align=center| 3 <br />
| align=center| [[Halite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Rhombohedral <br />
| align=center| 3 <br />
| align=center| [[Calcite]]<br />
| align=center| <br />
|-<br />
| align=center| Octhahedral <br />
| align=center| 4 <br />
| align=center| [[Fluorite]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| [[Diamond]]<br />
| align=center| Perfect<br />
|-<br />
| align=center| Dodecahedral <br />
| align=center| 6<br />
| align=center| [[Sphalerite]]<br />
| align=center| Perfect<br />
|}<br />
<br clear=all><br />
==Parting==<br />
<br />
Parting is the splitting of a gemstone along twinning or pressure planes.<br /><br />
Although this is similar to cleavage, parting can only be done along certain, well defined, planes of weakness and it is not reproducable like cleavage. Usually these parting planes are created during growth of a crystal when pressure was applied to the crystal causing it to (partially) break or fracture. Later overgrowth then heals the fracture, leaving a weak area inside.<br />
<br />
One of the most profound examples of parting is mica which concists of many very thin layers that can be easily parted with the fingernail. It is this mineral that is traditionally used for [[Polariscope#Quarter_wave_plates|quarter wave plates]].<br />
==Fracture==<br />
<br />
Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object along a direction other than then the direction of cleavage or parting. The most common type of fracture is termed "conchoidal" (shell-like).<br /><br />
<br />
The types of fracture are:<br />
* conchoidal<br />
* uneven<br />
* even<br />
* splintery<br />
* granular<br />
<br />
<br />
==Sources==<br />
<br />
* ''Gemmology'' (2005) - Peter Read<br />
<br />
==External links==<br />
<br />
* [http://www.galleries.com/minerals/property/parting.htm Parting]<br />
* [http://www.galleries.com/minerals/property/cleavage.htm Cleavage]</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Cleavage&diff=7486Cleavage2007-12-21T20:02:44Z<p>Nick Lombard: </p>
<hr />
<div>__forcetoc__<br />
<br />
==Cleavage==<br />
Cleavage is the splitting of a gemstone along the direction of its crystal faces where atoms have weaker bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction. The result of cleavage is a more or less flat plane with often a silky luster.<br /><br />
Cleavage is a reproducable property of a gemstone and can be done at any point of the cleavage direction.<br />
<br />
There are several directions of cleavage.<br />
* Prismatic cleavage<br />
* Basal cleavage<br />
* Pinacoidal cleavage<br />
* Octahedral cleavage <br />
* Rhombohedral cleavage<br />
<br />
The quality of cleavage is expressed with a few simple phrases.<br />
* Perfect<br />
* Good<br />
* Fair<br />
* Poor<br />
* None<br />
<br />
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]<br />
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]<br />
<br clear=all><br />
Stones and their cleavage directions:<br />
<br />
{| {{table}} width="50%"<br />
|-<br />
! Cleavage || Directions || Stones || Quality<br />
|-<br />
| align=center| Basal <br />
| align=center| 1 <br />
| align=center| topaz<br />
| align=center| perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| beryl<br />
| align=center| imperfect<br />
|-<br />
| align=center| Prismatic <br />
| align=center| 2 <br />
| align=center| peridot<br />
| align=center| perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| spodumene<br />
| align=center| perfect<br />
|-<br />
| align=center| Cubic <br />
| align=center| 3 <br />
| align=center| halite<br />
| align=center| perfect<br />
|-<br />
| align=center| Rhombohedral <br />
| align=center| 3 <br />
| align=center| calcite<br />
| align=center| <br />
|-<br />
| align=center| Octhahedral <br />
| align=center| 4 <br />
| align=center| fluorite<br />
| align=center| perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| diamond<br />
| align=center| perfect<br />
|-<br />
| align=center| Dodecahedral <br />
| align=center| 6<br />
| align=center| sphalerite<br />
| align=center| perfect<br />
|}<br />
<br />
==Parting==<br />
<br />
Parting is the splitting of a gemstone along twinning or pressure planes.<br /><br />
Although this is similar to cleavage, parting can only be done along certain, well defined, planes of weakness and it is not reproducable like cleavage. Usually these parting planes are created during growth of a crystal when pressure was applied to the crystal causing it to (partially) break or fracture. Later overgrowth then heals the fracture, leaving a weak area inside.<br />
<br />
One of the most profound examples of parting is mica which concists of many very thin layers that can be easily parted with the fingernail. It is this mineral that is traditionally used for [[Polariscope#Quarter_wave_plates|quarter wave plates]].<br />
==Fracture==<br />
<br />
Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object along a direction other than then the direction of cleavage or parting. The most common type of fracture is termed "conchoidal" (shell-like).<br /><br />
<br />
The types of fracture are:<br />
* conchoidal<br />
* uneven<br />
* even<br />
* splintery<br />
* granular<br />
<br />
<br />
==Sources==<br />
<br />
* ''Gemmology'' (2005) - Peter Read<br />
<br />
==External links==<br />
<br />
* [http://www.galleries.com/minerals/property/parting.htm Parting]<br />
* [http://www.galleries.com/minerals/property/cleavage.htm Cleavage]</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Cleavage&diff=7485Cleavage2007-12-21T20:02:19Z<p>Nick Lombard: </p>
<hr />
<div>__forcetoc__<br />
<br />
==Cleavage==<br />
Cleavage is the splitting of a gemstone along the direction of its crystal faces where atoms have weaker bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction. The result of cleavage is a more or less flat plane with often a silky luster.<br /><br />
Cleavage is a reproducable property of a gemstone and can be done at any point of the cleavage direction.<br />
<br />
There are several directions of cleavage.<br />
* Prismatic cleavage<br />
* Basal cleavage<br />
* Pinacoidal cleavage<br />
* Octahedral cleavage <br />
* Rhombohedral cleavage<br />
<br />
The quality of cleavage is expressed with a few simple phrases.<br />
* Perfect<br />
* Good<br />
* Fair<br />
* Poor<br />
* None<br />
<br />
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]<br />
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]<br />
<br clear=all><br />
Stones and their cleavage directions:<br />
<br />
{| {{table}} width="50%"<br />
|-<br />
! Cleavage || Directions || Stones || Quality<br />
|-<br />
| align=center| Basal <br />
| align=center| 1 <br />
| align=center| topaz<br />
| align=center| perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| beryl<br />
| align=center| imperfect<br />
|-<br />
| align=center| Prismatic <br />
| align=center| 2 <br />
| align=center| peridot<br />
| align=center| perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| spodumene<br />
| align=center| perfect<br />
|-<br />
| align=center| Cubic <br />
| align=center| 3 <br />
| align=center| halite<br />
| align=center| perfect<br />
|-<br />
| align=center| Rhombohedral <br />
| align=center| 3 <br />
| align=center| calcite<br />
| align=center| <br />
|-<br />
| align=center| Octhahedral <br />
| align=center| 4 <br />
| align=center| fluorite<br />
| align=center| perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| Diamond<br />
| align=center| Perfect<br />
|-<br />
| align=center| Dodecahedral <br />
| align=center| 6<br />
| align=center| Sphalerite<br />
| align=center| Perfect<br />
|}<br />
<br />
==Parting==<br />
<br />
Parting is the splitting of a gemstone along twinning or pressure planes.<br /><br />
Although this is similar to cleavage, parting can only be done along certain, well defined, planes of weakness and it is not reproducable like cleavage. Usually these parting planes are created during growth of a crystal when pressure was applied to the crystal causing it to (partially) break or fracture. Later overgrowth then heals the fracture, leaving a weak area inside.<br />
<br />
One of the most profound examples of parting is mica which concists of many very thin layers that can be easily parted with the fingernail. It is this mineral that is traditionally used for [[Polariscope#Quarter_wave_plates|quarter wave plates]].<br />
==Fracture==<br />
<br />
Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object along a direction other than then the direction of cleavage or parting. The most common type of fracture is termed "conchoidal" (shell-like).<br /><br />
<br />
The types of fracture are:<br />
* conchoidal<br />
* uneven<br />
* even<br />
* splintery<br />
* granular<br />
<br />
<br />
==Sources==<br />
<br />
* ''Gemmology'' (2005) - Peter Read<br />
<br />
==External links==<br />
<br />
* [http://www.galleries.com/minerals/property/parting.htm Parting]<br />
* [http://www.galleries.com/minerals/property/cleavage.htm Cleavage]</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Talk:Cleavage&diff=7484Talk:Cleavage2007-12-21T19:49:09Z<p>Nick Lombard: /* Cleavage, parting and fracture */</p>
<hr />
<div>== Cleavage, parting and fracture ==<br />
<br />
I put all 3 on the same page for now until there is more content. --[[User:Doos|Doos]] 08:32, 18 December 2006 (PST)<br />
<br />
<br />
Added a table for Cleavage example stones. Haven't found info on Pinacoidal cleavage or the quality of Calcite cleavage yet. --[[User:Nick_Lombard|nickl]] 02:46, 22 December 2007</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Talk:Cleavage&diff=7483Talk:Cleavage2007-12-21T19:48:46Z<p>Nick Lombard: /* Cleavage, parting and fracture */</p>
<hr />
<div>== Cleavage, parting and fracture ==<br />
<br />
I put all 3 on the same page for now until there is more content. --[[User:Doos|Doos]] 08:32, 18 December 2006 (PST)<br />
<br />
<br />
Added a table for Cleavage example stones. Haven't found info on Pinacoidal cleavage or the quality of Calcite cleavage yet. --[[User:nickl|Nick_Lombard]] 02:46, 22 December 2007</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Talk:Cleavage&diff=7482Talk:Cleavage2007-12-21T19:47:39Z<p>Nick Lombard: /* Cleavage, parting and fracture */</p>
<hr />
<div>== Cleavage, parting and fracture ==<br />
<br />
I put all 3 on the same page for now until there is more content. --[[User:Doos|Doos]] 08:32, 18 December 2006 (PST)<br />
<br />
<br />
Added a table for Cleavage example stones. Haven't found info on Pinacoidal cleavage or the quality of Calcite cleavage yet. --[[User:Nick Lombard|Nick Lombard]] 02:46, 22 December 2007</div>Nick Lombardhttp://www.gemologyproject.com/wiki/index.php?title=Cleavage&diff=7481Cleavage2007-12-21T19:42:45Z<p>Nick Lombard: Added cleavage examples</p>
<hr />
<div>__forcetoc__<br />
<br />
==Cleavage==<br />
Cleavage is the splitting of a gemstone along the direction of its crystal faces where atoms have weaker bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction. The result of cleavage is a more or less flat plane with often a silky luster.<br /><br />
Cleavage is a reproducable property of a gemstone and can be done at any point of the cleavage direction.<br />
<br />
There are several directions of cleavage.<br />
* Prismatic cleavage<br />
* Basal cleavage<br />
* Pinacoidal cleavage<br />
* Octahedral cleavage <br />
* Rhombohedral cleavage<br />
<br />
The quality of cleavage is expressed with a few simple phrases.<br />
* Perfect<br />
* Good<br />
* Fair<br />
* Poor<br />
* None<br />
<br />
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]<br />
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]<br />
<br clear=all><br />
Stones and their cleavage directions:<br />
<br />
{| {{table}} width="50%"<br />
|-<br />
! Cleavage || Directions || Stones || Quality<br />
|-<br />
| align=center| Basal <br />
| align=center| 1 <br />
| align=center| Topaz<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| Beryl<br />
| align=center| Imperfect<br />
|-<br />
| align=center| Prismatic <br />
| align=center| 2 <br />
| align=center| Peridot<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| Spodumene<br />
| align=center| Perfect<br />
|-<br />
| align=center| Cubic <br />
| align=center| 3 <br />
| align=center| Halite<br />
| align=center| Perfect<br />
|-<br />
| align=center| Rhombohedral <br />
| align=center| 3 <br />
| align=center| Calcite<br />
| align=center| <br />
|-<br />
| align=center| Octhahedral <br />
| align=center| 4 <br />
| align=center| Fluorite<br />
| align=center| Perfect<br />
|-<br />
| align=center| <br />
| align=center| <br />
| align=center| Diamond<br />
| align=center| Perfect<br />
|-<br />
| align=center| Dodecahedral <br />
| align=center| 6<br />
| align=center| Sphalerite<br />
| align=center| Perfect<br />
|}<br />
<br />
==Parting==<br />
<br />
Parting is the splitting of a gemstone along twinning or pressure planes.<br /><br />
Although this is similar to cleavage, parting can only be done along certain, well defined, planes of weakness and it is not reproducable like cleavage. Usually these parting planes are created during growth of a crystal when pressure was applied to the crystal causing it to (partially) break or fracture. Later overgrowth then heals the fracture, leaving a weak area inside.<br />
<br />
One of the most profound examples of parting is mica which concists of many very thin layers that can be easily parted with the fingernail. It is this mineral that is traditionally used for [[Polariscope#Quarter_wave_plates|quarter wave plates]].<br />
==Fracture==<br />
<br />
Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object along a direction other than then the direction of cleavage or parting. The most common type of fracture is termed "conchoidal" (shell-like).<br /><br />
<br />
The types of fracture are:<br />
* conchoidal<br />
* uneven<br />
* even<br />
* splintery<br />
* granular<br />
<br />
<br />
==Sources==<br />
<br />
* ''Gemmology'' (2005) - Peter Read<br />
<br />
==External links==<br />
<br />
* [http://www.galleries.com/minerals/property/parting.htm Parting]<br />
* [http://www.galleries.com/minerals/property/cleavage.htm Cleavage]</div>Nick Lombard