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Commentary: The Business

Cara Williams: An Endangered Species



The Business: An Endangered Species

Hunting down the last untreated gemstone


Published in the May 2013 issue

He was the global poster child for a species going extinct. “Lonesome George,” a Pinta giant tortoise in the Galapagos Islands, recently passed away, the very last of his breed. It made me think: Will future generations have to go to the ends of the earth — or a museum — to see natural, untreated gemstones?

It is tempting to say, “If it can be treated, it probably has,” but this is hardly fair to all those natural beauties out there that don’t require plastic surgery.


Plastic surgery is an analogy that’s closer to the truth than you might expect, as plastics and their polymer cousins are now seen in a variety of gem materials. But let’s be clear: This proliferation of treatments is seen primarily in inexpensive gem materials. Not much has changed at the high end, even though most high-end stones are now accompanied by lab reports.

Theoretically, non-treated gems should have a greater value, as stones that are naturally beautiful are rarer.

Today, polymers, such as Opticon, play a common role in the finishing process of gems. Any stone with surface-reaching fissures can be treated in this way. Opticon, or oiling, makes small cracks and fissures much less visible and boosts clarity. A thorough cleaning will typically remove some of the filler, and the result is a stone with lower clarity — and often lower color. Emeralds are best known for this treatment, but also alexandrites, apatites and tourmalines — anything that tends to have inclusions. Even garnets and quartzes can occasionally be found with traces of Opticon. Opticon is the exception to every rule that follows.

Coatings have also changed the game. CVD processes are commonly applied to the pavilion of many gems. Mystic topaz is best known for receiving these treatments. Coating a goshenite (colorless beryl) pink gives the look of morganite (naturally pink beryl), and it will also test as expected for morganite on a refractometer. Good gemologists can easily miss these once set in jewelry. Most are only discovered after some of the coating has worn off. Any stone can be coated. So now we have two exceptions to the rules.

Garnets have traditionally not been treated. With the exception of Russian demantoids, this is still the case. Rumors persist, but there is not much potential for improvement. Spinels have long been known to be all natural. Most still are, but current research indicates that heating may improve some colors. Peridots are a safe bet. Less common stones that are expected to be natural include chrome diopside, iolite, fire opal and chrome tourmaline … with the previously mentioned exceptions!

Theoretically, non-treated gems should have a greater value, as stones that are naturally beautiful are rarer, but for this to actually happen, the market must recognize them.


Lack of treatment alone will not increase a stone’s value; it must also be fine quality. Untreated stones like emerald, ruby, sapphire and diamond command premiums over similarlooking — but treated — gems. When treatments change a stone’s value, the FTC requires it be disclosed. To protect yourself, get educated. Or hire a good gemologist.


Cara Williams, along with her husband Bear Williams, is a partner in Stone Group Labs and Bear Essentials Fine Colored Stones.



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