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A word about natural gemstones

Posted by Yvonne Raley on

So I practically got yelled at. This was by a gemstone dealer at a jewelry show last spring, in response to my question about his tourmalines. “All stones are natural. Heated is not the same as treated.”

I had asked if the stones were heated, and that is a legitimate question to ask about tourmalines. Some tourmalines are heated and some aren’t, which affects the price.

Why, then, did my question inspire such an outburst? The dealer was right in two ways, wrong in another way. He was right to say that all gemstones are natural. That claim simply means that the stone is not synthetic. “Natural,” in the gemstone business, means more or less what it means when it comes to poultry. All poultry is natural, what else would it be? It just may not be free range or organic.

The dealer was also right if his claim simply was that most gemstones are heated (especially the “precious stones”), and that this is both common and acceptable practice. As opposed to glass filling, diffusing, dyeing, or surface coating, for example.

But of course, heat treatment is a treatment! Stones are heated for several reasons: heat treatment can change color, it can intensify color, it can lighten color, and it can improve clarity. Sapphires, rubies, aquamarines, tanzanite and many amethyst, for instance, are typically heated. Almost all blue topaz are heated. Heat treatment makes more material available to the mass market, which in turn lowers the price.

If you want a completely unadulterated stone, you have to ask very precise questions, and you have to be able to trust your source. Untreated stones don’t always have the same brilliance as heated stones (sapphires and rubies are a good example), and more inclusions are visible. Evidence of heat treatment is hard to detect, and even many jewelers won’t know how their stones have been treated. So when you buy jewelry, you have two options: you can assume the stones were heated and not worry about it, or you can ask directly about heat treatment. If the seller doesn’t know or tries to fudge the answer, assume that’s a “yes”.


Untreated Aquamarine (1.91 cts) with Visisble Inclusion

To me, aside from the fact that I love the natural beauty of things, it is the chase for the untreated stone that appeals. Here’s a quote from Matlins’ and Bonnano’s Jewelry & Gems: The Buying Guide, that explains my sentiment: “Especially fine natural gemstones are rare and more costly than ever before. This scarcity has affected what is available in jewelry stores, and the choices available to consumers. Natural emeralds, rubies, and sapphires – that is, gems not subjected to any type of artificial treatment or enhancement-have never been rarer than they are today. While they can still be found, locating a natural gem in a particular size can take months of intensive searching, and when found, commands a price prohibitive to all but the most serious collector or connoisseur.” (P. xiv) The authors then give the example of a natural emerald of over 3 carats that took them months to find and fetched a price of $100,000, wholesale.


Untreated Columbian Emerald, .82 cts

Natural gems, even precious ones, don’t have to be quite that expensive. The issue here, as with so many things, is size. Stay under a carat, under ¼ carat even, and you have something much more affordable. If you have a source you can trust. And that may be the hard part.


Sandblasted Ring with 2mm Untreated Burma Rubies

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