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GEM EDUCATION : Information on Gem Treatments

Today buying an absolutely natural gem is an exception than the rule. Gem treatments are practiced since the antiquity to enhance their overall appearance and nowadays most gems are treated one way or another. A treatment is not always enhancement. For instance, two gems may appear similar, but when they are treated exactly under the same conditions their resultant appearance may be different, the appearance in one stone may be improved, while in the other stone may be worsen or diminished. Although the gemological properties in most treated gems remain essentially the same, their physical and chemical properties are altered. In treating gems there are many "gray areas" that deserve special attention and consideration.

Examples of Gem Treatments of the Big Four
	Diamond. Occasionally irradiated and/or heated to produce yellow, green and other fancy colors; the process is not stable. Often, diamonds are laser-drilled to improve clarity/color; the process is stable but controversial. Occasionally coated to improve their color; the process is stable. Often, filling the cracks/cavities with/without colored fluxes to improve clarity; stability is variable. Brownish diamonds may be subjected to HTHP process to produce white colors; the process is reportedly stable and irreversible..
	Emerald. Commonly treated by inducing colorless or colored oils, resins, oleoresins with or without hardeners from its surface-reaching cracks into the gem's interior to improve clarity/color; the treatment is not stable and special handling/care is required. The process is reversible.
	Ruby. Commonly heated to reduce purple tinge, blue patches, remove silk and improve color. Commonly filling the surface-reaching fractures and surface cavities/pits with additives to improve clarity and/or color; these heating processes are stable.
	Blue Sapphire. Commonly heated in various methods with/without additives to improve/develop new color; the treatment is stable. Occasionally, surface color diffusion treatment produce uniform blue color which can be removed after repolishing the stone.

Types of Gem Treatment processes & gem treating equipment. Gems are subject to irradiation, thermal, chemical and other types of treatments. Often, several types of different treatments are applied to the same gem as part of the process sought. For instance, in treating near-colorless topaz, certain dose of irradiation is applied first, followed by heating to obtain the final blue color we all see at the jewelry store display counters. The results obtained after the gems are treated varied greatly. This is true in heat-treating ruby-sapphire where the reliability of the equipment and technology used in the process is of paramount importance. To view images of various furnaces and equipment used in gem treating click here

Most important types of treatments applied to gemstones
Type of Treatment	Examples of Treated Gemstones
	HEATING: Ruby, Sapphire, Beryl, Tourmaline, Zircon, Quartz
	FRACTURE FILLING: Ruby, Sapphire, Emerald, Diamond, Tourmaline
	RADIATION: Diamond, Beryls, Quartz, Topaz, Tourmaline, Pearl
	DYEING: Jade, Agate, Sodalite
NOTE: Only certain types of above listed sample gems are treated and not always

To learn more about these gem treatments (among with Laser-Drilling, Bleaching, Coating, HTHP, Impregnation, Surface-Color-Diffusion, etc.) please refer to Ted Themelis' books Gem Treatments & Enhancements (in print), Flux-Enhanced Rubies & Sapphires, The Heat Treatment of Ruby & Sapphire and Beryllium-Treated Rubies & Sapphires. Also, check Gemlab Reports #GR2-01 (Oiling emeralds) & GR2-06 (Ruby-filling process).