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  The abuse of all that is natural:
The lead glass-filled ruby intrigue


By Menahem Sevdermish, D.Litt. FGA
September 10, 2014


To me the word "natural" in gems is sacred, and ideally should refer only to gemstones that were created in nature, not having undergone any process other than cutting, polishing and cleaning.

Yes, we have seen rubies heated for centuries to remove "silk," and sometimes to improve their red color by eliminating blue components. And yes, we have also seen some almost milky white geoda sapphires from Sri Lanka and Madagascar (Andranandambo and Ilakaka) turn velvety blue after being subjected to high temperatures, using fairly simple ovens.

I can bite my tongue and, on condition that there is a clear disclosure, consider these procedures to be legitimate, for no additional material is added to the product. A similar heating process may even occur in nature. Indeed, it generally is accepted that such product may be referred to as "natural" ruby or sapphire.

But beyond that point, the unqualified use of the word "natural" is more problematic. Such certainly is the case with heat treatments involving additives, where the diffusion of foreign materials occurs on the surface of gems, filling fissures, cracks and cavities.

Beryllium is an element that can produce spectacular results. A light matter, it penetrates the material inner layers, producing amazing colors. When these goods first appeared on the market, undisclosed I may add, certain laboratories were quick to produce thousands of reports for beautiful Padparadcha sapphires, without suspecting the obvious and questioning where they came from.

In the gem business it sometimes feels that we are part of a Greek tragedy, where our fate appears sealed and we are doomed to a bleak future.

When the beryllium fraud was finally revealed, it shook the gem world and ruined consumer confidence in a number of major centers, sometimes giving rise to a demand that no sapphire be used unless it was were free of any treatment. It caused, what I call, the ETQ, or "Excess Time for Questions", during a sales session, where you or your salesperson would find yourselves spending precious time explaining that your gems are legitimate, instead of concentrating on how beautiful they are.

ETQ has certainly been the regular practice over the past decade with glass-filling corundum treatments. Here, low quality rough semi-opaque corundum, full of cracks, fissures and cavities that have been pre-cleaned to remove dirt and oxidized remnants, are impregnated with lead-enriched silica-based glass. The effect is startling. The filled cracks allow the light to travel through the material giving it the appearance of a real ruby, worth many times more than the ugly rough from which it originated. In the more extreme cases, the leaded glass actually acts as cement that joins several pieces of corundum together, creating what seem to be one big stone.

But that's only part of the story. At a Bangkok fair several years ago, I saw a certificate that clearly stated that such a treated product was a "natural ruby, natural corundum." Indeed, all that may have suggested otherwise was a comment at the bottom of the document that mentioned that some (leaded) glass had been "found in fissures."

Such certificates still pop up from time to time, especially in online trading platforms.

How far do we have to go with treatments in order to discard the magic word "natural"? Will a product made out of corundum powder that has been mixed with leaded glass still be called a natural ruby?

Well friends, let's clear things up. A ruby is a natural red corundum with chromium and iron as the coloring elements. It is not a treated corundum filled with leaded glass. That should be properly called treated corundum, impregnated by lead to create a ruby imitation.

I have been saying this for years and have sometimes felt that I was a lone voice in the wilderness. I was continuously met with somewhat hesitant detractors who would state that "this is still a ruby, with a remark in the certificate," or "the original material is natural corundum." I almost thought the battle was lost.

But it seems that I was not the only one who thought this way. The Laboratory Manual Harmonization Committee (LMHC), which bring together representatives of gem labs from the around the world, decided the take an uncompromising stand. For an "assembled multitude of unrelated tiny pieces" they created a new classification: "Corundum with/and glass (manufactured product)."

Let's be clear. There is no mention of any natural origin. In fact, to eliminate any misunderstandings, LMHC added a mandatory comment: "This item is a combination of glass and ruby/sapphire or corundum".

Although this may seem to be overkill to some people, the LMHC classification is an important move in the right direction. Such a classification will differentiate between the natural gem and its composite counterpart.

In my humble opinion, we should even protect natural gems with a separate, natural certificate, which will look different from the treated gems certificate.

I urge you, my colleagues, to take an action. Let us protect what is sacred and not abuse the word "natural." Let's cherish those truly precious gems for what sets them apart from the crowd.

Comment from Christopher Smith, American Gem Lab (AGL) owner:
"Firstly, let me say that I agree with your statements. I would just like to add some further clarification for you regarding the disclosure of these lead-glass treated stones.
In 2007, I was the first to take a definitive position on this material by classifying all of the material as Composite Ruby. Without the use of the term 'natural'. Clearly distinguishing this material from other forms of treated, natural ruby/corundum in the market."

Menahem's response:
You are quite right Chris! But, I shouted louder! ;-)

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