It's a fact of life in the gemstone industry that many gems are treated. The most common form of treatment is heat treatment, which is applied routinely to ruby and sapphire, and to other gems such as tanzanite, blue zircon and blue apatite. Some gems, such as blue topaz, are irradiated to produce their distinctive color; in fact it's virtually impossible to buy a blue topaz which has not been irradiated. Other gems, such as emerald, are treated with oils or resins to fill fractures. More recently, we've seen heat treatment with beryllium diffusion for yellow and orange sapphires, and fracture-filling with lead glass for African rubies. Sometimes it seems like the gem world is awash in gem treatments.
The idea of treating gems is hardly new. Pliny's Natural History, the compendium of knowledge from ancient Rome written in the first century A.D., discusses a range of techniques for altering gems, including heating, oiling, dyeing and the use of foil backings and coatings. Some of those ancient techniques were undoubtedly deceptive, but today gem treatments are just a way for the industry to meet world demand for gemstones in the face of very limited supply.
Despite the proliferation of gem treatments, there are still many choices for buyers who insist on an untreated gem. You don't need to pay a fortune for very rare untreated sapphires or rubies. There are a number of gemstone varieties that combine good gemstone characteristics -- hardness, durability, brilliance and clarity -- with outstanding color, yet are never treated. You can buy these with confidence, knowing you are buying a completely natural gem. Here are our recommendations for untreated gem varieties:
- First Published: March-28-2008
- Last Updated: March-01-2011
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