Special Report: Colored Gems Emeralds

Renewing trust in a new, promising and reportedly stable emerald treatment has hit the market. Composed of a secret patented formula of synthetic resin and hardener, it is touted as the latest and best solution for reducing eye-visible inclusions and increasing emerald durability.

It’s called the Arthur Groom & Co.-Gematrat treatment – named for the companies that developed it. The developers created the treatment in hopes of restoring waning consumer confidence in emeralds. But most importantly, it’s designed to be easier than other emerald treatments to detect.

The new treatment also appears to have greater lasting power than its two main rivals: Opticon, used mainly in Brazilian emeralds, and palm oil, used mainly in Colombian emeralds. The use of Opticon and palm oil (which also are synthetic resins), coupled with a widespread reluctance to disclose treatments, are largely blamed for stimulating confusion and woe in the emerald business in the past few years.

Gematrat, which invented the treatment in Bogota, Colombia, and Arthur Groom & Co., New York City, say they’ve tested the material for more than four years. It has shown far greater resistance to oxidation, general breakdown over time and deterioration under trying conditions, they say. “We submitted test stones to excruciating whole-day ultrasonic tests, placed them under steamers and subjected the stones to heat at 300°C without shrinkage, leakage or other problems,” says Arthur Groom.

The two companies say they’ve also developed technology to completely remove the new filler – or any other known emerald filler – a task that was difficult or impossible to do before. This, they hope, will bolster the emerald market because jewelers now can have fillers removed or replaced more thoroughly than ever before.

Under the spotlight

Curious? So are a few well-known emerald dealers who have signed on to the treatment program and are openly optimistic. “I have sent them half a dozen stones in the $4,000-per-carat range and I’m pretty impressed,” says Ralph Mueller of Ralph Mueller & Associates, Scottsdale, Ariz. “They seem to be able to clean a stone completely so it will accept treatment better. This is important because sometimes particles of an an old treatment will block the flow [of treatment resins or oils], resulting in a partially treated stone.”

Ray Zajicek of Equatorian Imports, Dallas, Tex., another emerald dealer, has already put a treated emerald to some stringent tests. “I ran it through the ultrasonic all day. No change,” he says. “I put it under a light bulb all day wrapped in cotton to catch seepage. No change. I steamed the stone. No change. Think of the implications from a retailer’s point of view. It’s great because he will have a stone that will not change on him, even if it goes through an ultrasonic!” [Editor’s note: Generally, retailers avoid putting emeralds in an ultrasonic cleaner because some can’t withstand the heat and vibration.]

C.R. “Cap” Beesley, president of the American Gemological Laboratories, New York City, also conducted some preliminary examinations. “I am going through some of the stones and making observations,” he says. “The key will be in being able to identify this process as different from the others because I imagine there will be imitators. But I think the filler has real potential if it truly performs the way Arthur Groom has described. We will now do our homework.”

There are skeptics. Some dealers say another treatment will only confuse the emerald market more. Groom-Gematrat developers, however, say their treatment will offer the emerald business a greater degree of knowledge and confidence.

Other critics have doubts because the treatment is not “natural.” And still others prefer more traditional treatments. “Cedarwood-treated emeralds have a very good track record for stability over time – twenty years of use and market acceptance,” says Ron Ringsrud of Constellation Colombian Emerald Co., Saratoga, Cal.

Whatever the case, the debate over emerald treatments is sure to heat up. The outcome may well dictate the type of treatment seen in emeralds in the years to come.

Selling points and a caveat

The Groom-Gematrat treatment is inserted into surface-reaching cracks and fissures, thereby increasing long-term durability and visual clarity, the developers say.

Questions abound as to whether the new treatment truly differs from other synthetic treatments. Groom, a 23-year veteran of the gemstone business, points to several distinct differences. But he is the first to admit there is one significant caveat – no testing has been conducted by an independent gemological laboratory, though tests conducted at a scientific lab in Colombia appear to support the view the new treatment has lasting power.

Several gem labs have signaled interest in the treatment, including the Gemological Institute of America. “GIA plans a major study on Gematrat and other comparison oil and resin treatments,” says Mary Johnson, Ph.D., a GIA research scientist. Though the research details have not yet been worked out, she anticipates the study will culminate in a feature article in GIA’s quarterly Gems and Gemology publication.

Groom-Gematrat-treated stones have been sent already to the SSEF Laboratories and the Gübelin Laboratories in Switzerland. The Gemmological Association of Great Britain also has expressed interest in buying test samples. Groom says he encourages such testing.

A firm believer in treatment disclosure, Groom also wants to establish identification techniques to help the trade understand, identify and separate the new treatment with ease. Groom already is testing a “tracer” in the treatment that fluoresces to help separate it from natural and other synthetic material. The reason: the ability to distinguish the material easily will add a large measure of confidence to the emerald trade, he says.

Groom says the major selling points include:

  • The material can be removed. If a buyer insists on knowing what a gemstone looks like untreated, the treatment can be removed and the stone later treated again. If a customer wants an untreated stone, the filler can be taken out entirely.

Groom points to a series of identification reports to support his claim. He sent a treated emerald to GIA and got back a report saying “evidence of clarity enhancement is present.” He removed the treatment and sent the same emerald to GIA. The second report from GIA indicated the emerald was natural and that “no evidence of clarity enhancement was detected.”

The Groom-Gematrat treatment cannot be removed by conventional methods, acids (though acids will affect it) or heat up to 300°C, factors Groom-Gematrat’s own studies have shown. Groom confirms he and his associate, Oswaldo Lissardo, the treatment’s discoverer, have the machinery and technology to remove the treatment. The process is not harmful to the emerald, says Groom, and GIA certification backs that up. In fact, the developers also offer a service to remove all fillers, including cedarwood oil, palm oil, Canada balsam and Opticon. “The ability to totally remove foreign material from a gemstone is utterly crucial to the success of our treatment thereafter,” says Groom.

  • It’s distinctive enough to be detected and disclosed. The refractive index of emerald is 1.577-1.583. The closer a filler’s refractive index is to emerald’s, the more completely the filler “covers” or hides surface-reaching flaws. But while hiding flaws may seem the obvious goal, what happens thereafter is the crux of the problem. A buyer who can’t detect any treated flaws may think he or she is buying something far more valuable and beautiful than it actually is. That’s a case of obvious deception.

Palm oil has a refractive index of 1.570, pretty close to emerald’s. The Groom-Gematrat filler has a refractive index of 1.534 (+/-), which its developers say provides sufficient differentiation from natural gems while still ensuring the beauty of the emerald. “This allows us to be completely up front about the treatment while making emeralds available to a whole market of people who cannot afford completely natural gem emeralds,” says Groom.

Ron Ringsrud, who also examined some Groom-Gematrat emeralds, says his most lasting impression of the product was its refractive index. “Whether by design or by chance, it really solves a number of problems,” he says. “One is that with a 1.534 R.I., you eliminate the ‘flash effects’ and, therefore, don’t confuse the product with palm oil or Opticon. More importantly, the relatively lower R.I. allows it to be detected more easily under magnification without sacrificing the quality of clarity enhancement.”

  • It can withstand heat and remain colorless. Groom-Gematrat literature says the material is stable under common cleaning or bench procedures. It also says the filler – unlike many other treatments – can withstand heat, such as from a steamer or at the cutting wheel. “We recut two stones [with the Groom-Gematrat treatment] and they turned out fantastic,” says Jack Sabzevari of New York Gem Corp., New York City. Groom says several dealers have cut or recut good-to-finer emeralds that have undergone the Groom-Gematrat treatment without adverse effects.

One note of caution: emeralds with a disproportionate number of flaws that could endanger the stone should not be put under this kind of testing.

Meanwhile, Opticon and cedarwood oil may oxidize and turn yellowish or brownish with moderate heat, repeat treatments and over time. And palm oil may show a milky white residue with repeat treatments. Some dealers say oxidation is a moot point because of the relatively small amount of treatment in a stone. “When viewed in the thickness that will be found in emerald fractures, it remains colorless,” says one gem dealer.

But Zajicek says the fact the Groom-Gematrat treatment remains colorless over time is an important factor.

  • It doesn’t drain. Palm oil without a sealant can ooze out of a stone over time due to such simple forces as gravity or cabin pressure in an airplane. Less viscous fillers – such as vegetable, mineral and cedarwood oils – are especially prone to drainage and then must be re-treated, say emerald dealers.

Stones initially treated with palm oil without a sealant often have to be re-treated throughout the selling cycle to maintain “coverage.” The consumer, who may not know about treatments, is often overlooked in this process. And this leads to questions about who to approach for a refund or to have the stone re-treated. “Why not treat it just once?” asks Groom. Adds Zajicek: “Being able to clean an emerald ring with confidence is an improvement. If I were a jeweler, I would be looking hard for emeralds that look the same over time and do not change.”


Expectations for any solution to problems facing emerald are high, given its history and coveted position in the industry. Some will argue that emerald’s woes have been greatly exaggerated in recent years. It’s true that treatment and its disclosure are not at the heart of every emerald problem. Other factors include the economy in consuming countries such as Japan and Thailand, supply shortages and even the dictates of fashion.

However, emeralds are different from other gems in the way they are romanced and sold. Most natural emeralds have surface-reaching flaws and other internal characteristics. In no other gemstones have these flaws been romanced with as much passion. Emerald fanciers even rhapsodize about jardins or gardens. But when alluring adjectives are simply not enough,

treatment is used to soften or conceal these gardens. This has gone on since at least since 55 A.D., when Pliny the Elder reported steeping smaragdi [emeralds] in oil to improve them.

Now almost 2,000 years later, we are still trying to improve the look of an emerald’s natural flaws. For Groom & Co. and Gematrat, their new treatment represents a hope for transparency in emeralds. They say it also sends a signal of renewed strength to the emerald business because of its durability, apparent permanence, removability and ease of detection. Groom-Gematrat is off to a good start, at least according to New York Gem Corp.’s Jack Sabzevari. “I have seen every method I can think of,” he says. “This is the only method I will put my money into because it is the only legitimate one I have seen in 25 years.”

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