Color
From The Gemology Project
This section is currently under construction, do not edit until this message is gone | |
Doos 12:27, 13 August 2006 (PDT) |
Hue
Color | Code | Name |
---|---|---|
R | red | |
oR | orangy red | |
RO/OR | red-orange or orange-red | |
rO | reddish orange | |
O | orange | |
yO | yellowish orange | |
oY | orangy yellow | |
Y | yellow | |
gY | greenish yellow | |
YG/GY | yellow-green or green-yellow | |
styG | strongly yellowish green | |
yG | yellowish green | |
slyG | slightly yellowish green | |
G | green | |
vslbG | very slightly bluish green | |
bG | bluish green | |
vstbG | very strongly bluish | |
GB/BG | green-blue or blue-green | |
vstgB | very strongly greenish blue | |
vslgB | very slightly greenish blue | |
B | blue | |
vB | violetish blue | |
bV | bluish violet | |
V | violet | |
vP* | violetish purple* | |
P | purple | |
rP | reddish purple | |
RP/PR | red-purple or purple-red | |
stpR | strongly purplish red | |
slpR | slightly purplish red | |
R | red | |
Pk | pink (exception) | |
Brn | brown (exception) | |
*This was changed from bP (bluish purple) |
Tone
Tone | Scale | Name |
---|---|---|
0 | colorless or white | |
1 | extremely light | |
2 | very light | |
3 | light | |
4 | medium light | |
5 | medium | |
6 | medium dark | |
7 | dark | |
8 | very dark | |
9 | extremely dark | |
10 | black |
Causes of color
The causes of color can be divided into 4 different theories:
- The Crystal Field Theory
- Transition metal compounds (Malachite, Almandine)
- Transition metal impurities (Emerald, Citrine, Jade)
- Color centers (Amethyst, Maxixe-beryl)
- The Molecular Orbital Theory
- Charge transfer (Sapphire, Iolite)
- Organic coloration (Amber, Coral)
- The Band Theory
- Conductors (Copper, Silver, Iron)
- Semi-conductors (Galena)
- Doped semi-conductors (Diamond)
- The Physical Properties Theory
- Dispersion (Fire in Diamond)
- Scattering (Moonstone, Cat's eyes, Stars)
- Interference (Iridescence, Opal)
- Diffraction (Opal)