Gemstone Treatments and Enhancements

From The Gemology Project
Revision as of 13:40, 14 September 2009 by Barbra (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

A Brief History of Gemstone Treatments

Gemstones have been treated to improve their color since ancient times. Heating was fist described as a way to improve color in sapphire by Pliny the Elder!

There are three methods which have endured the test of time, both in stability of treatment and in success of the procedure. They are heating (more accurately burning), irradiating and dyeing.

Dyeing

Dyeing is best suited for porous gems which can easily be impregnated with foreign coloring agents, such as agates or turquoise. But if a gem is riddled with surface reaching fractures, dye can be absorbed within these fractures and rather dramatically alter the color of a gem.

Heat Treatment

Heat treatments are normally performed with temperatures that vary from a few hundred degrees to well over 1700 degrees Celsius. Gems that are routinely heat treated are citrine, corundum (both sapphire and ruby), aquamarine, morgainite, pink topaz, tanzanite, tourmaline and zircon. It is not always easy to detect whether or not a gem has been heat treated using standard gemological instruments, especially when the treatment is done at a relatively low temperature. In the case of ruby and sapphire, treatments involve extremely high temperatures and can often be detected with microscopic observation of internal changes and characteristics, especially apparent with inclusions and areas of tension.

Irradiation

Very early attempts to improve the color of diamonds involved the use of radium. Diamonds were buried in radium salts for period of up to one year. The resulting color was green which was thought to be an improvement over their original "Cape" tones, but the caveat was that the treated diamonds became radioactive. Today, techniques for irradiating gemstones are much more sophisticated. As with heating detection can be difficult.