A dramatic fall-off in worldwide demand for emeralds is forcing Colombia to face up to the primary cause: gemstone treatment and a need for proper disclosure.

Much of the Colombian production is impregnated with resins and epoxy resins, such as palm oil or Opticon, as well as with more traditional treatments. But so little is being disclosed that dealers are refusing to handle it. Says one emerald dealer who prefers to remain anonymous: “I reject 95% of the emeralds I see.”

Colombian authorities aren’t willing to pin the blame for declining sales directly on treatment or disclosure of treatment. Rather, they bring up the issue as only one of a number of factors affecting their industry – including the need to modernize their mining, manufacturing and jewelry-making activities; to show more initiative in mining fresh deposits; to make access to the mines safer; and to develop a major marketing plan for emeralds.

Yet to dealers of Colombian emeralds, especially those in the U.S., the treatment issue is paramount. “There is a crisis of confidence in emeralds in general,” says Ron Ringsrud, a dealer based in Saratoga, Cal. “The lack of confidence is based on general confusion over the whole treatment issue. For example, because a gem is from Colombia, many fear it has been treated with resins.” Because of this uncertainty, says Ringsrud, Italian manufacturers have reduced their emerald orders by 50% and sales to Japan have dropped some 17%. Overall, he says, “Colombian sales have suffered at least a 40% drop.”

The stakes are huge for Colombia’s gemstone industry, indeed for the nation’s entire economy. “Minerals comprise 23% of our GNP and our goal is to increase that to 55%” says Dr. Rodrigo Villamizar Alvargonzalez, Colombia’s minister of mines and energy. “We would like to position the emerald as going from a second-class citizen to a first-class citizen.” The country produces about 60% of the world’s total emerald output.

If Colombia is to realize this goal, it must rebuild international confidence in its emeralds. Dr. Antonio Jose Sanchez Murillo, general manager of Mineralco, a private company that runs government projects, says the government is considering a number of actions toward that end, including:

  • Creation of Colombian gem labs to study treatments, their permanence and disclosure requirements.

  • Development of an emerald bourse or central buying area in Colombia.

Both projects would help to build trust among buyers of Colombian emeralds, say dealers. Colombia also is looking at various plans to promote its emeralds, including the possibility of underwriting an emerald promotion in cooperation with the International

Colored Gemstone Association. ICA ran a well-publicized international promotion on behalf of ruby last year; Colombian officials believe one on emerald could be at least as successful. They note that in a number of polls in the U.S., consumers chose emerald as their favorite gemstone.

Dealers in Colombian emeralds are more blunt than the Colombians in saying what is needed to encourage them to buy freely in the local market. They want full disclosure of treatment, improved safety for buyers when they visit Bogota and the emerald mining areas, and competitive prices. They also want a duty-free policy for importing diamonds and other rough gemstones and recommend development of the talents of local goldsmiths and artisans.

On the disclosure issue, some dealers believe it’s enough to identify resin-treated gemstones clearly; they don’t seek to ban the material, as more active critics of the resin do. For example, Ray Zajicek of Equatorian Imports, Dallas, Tex., a veteran emerald dealer, says the Opticon treatment issue is much ado about nothing. “Opticon by itself is not a misrepresentation,” he says. “There’s nothing wrong with any treatment if we’re dealing with a colorless substance, disclosing it and, as an end result, making the gemstone more attractive and/or durable.”

Many of these issues were discussed during an international forum in Bogota in November (see JCK, January 1997, p. 170). The discussion will continue at a larger, Colombia-sponsored World Emerald Congress in July.

The need for positive action to regain world confidence in Colombian emeralds came up time and again at the November forum. “We have not had the vision to expand,” Alvargonzalez said at the forum. “[The emerald business] has been nothing more than exploitation since the Spanish conquest. And yet the richness of our economic sectors is enviable. We have yet to see what the wonders of the earth have in store for us.”


Emerald treatment is not new. Canada balsam, cedarwood, linseed, rapeseed and even olive oils have been used for centuries to fill fractures in emeralds; most industry members accept this as standard practice. But when the substance used is an epoxy resin such as Opticon, many think the intent is to hide a stone’s flaws, not just minimize them.

Here’s how the treatment works. Emeralds with surface-reaching cracks are coated with epoxy resin or the substance is vacuum-pumped into the fractures. After excess resin is wiped off, a hardening agent is applied to seal the opening. Because the refractive indexes of the resins often are quite close to that of emerald, the effect is indeed to hide a stone’s flaws.

A majority of emeralds sold today are impregnated with epoxy resin. That’s OK if buyer and seller both know it, but detection of synthetic resins is quite difficult. This makes fraud or misrepresentation a real possibility and disclosure far from universal even among the well-intentioned.

Here are some suggestions to help you spot epoxy-filled emerald:

  • Using magnification and a bright light such as a fiber-optic source, look for a “flash effect” along the plane of contact between the gem and the epoxy filler. The flash effect has not been documented in oiled gems. You may need to manipulate, rotate and turn a gem to find the flash effect, because it appears only at a plane perpendicular to the direction of the light source. Once you find a flash effect, rock the gem slowly to see if the dispersion color changes from orangy-yellow to blue. (Note that lack of a flash effect doesn’t guarantee a stone has not been resin-treated.)

  • Gas bubbles sometimes form in the resin, especially in larger gaps or fissures within the gem. They will have a characteristic flattened-bubble “doughnut” shape. Other bubbles appear whitish and lobular or sometimes dendritic and are described as very reflective.

  • You may see the openings of fissures when you use reflected light to examine an emerald’s surface. If you follow the path of the crack, you may note a low-relief distinction between the emerald and the filled void. This may show a gem is filled, but won’t prove what filling was used.

  • Again seek the entrance of a surface-reaching fissure. Swiss gemologist Dr. H.A. Hanni suggests putting a heated needle next to the opening; the filling will melt and move slight-ly. The examination should be performed very carefully and through a microscope, he says. This could be considered a destructive test and should be used only as a last resort. Hot needle tests also could cause an oiled gem to “sweat,” a slightly different result.

R.I. Durability Solvent Prevalence Ease of Detection Permanence
Emerald 1.577 1.583 Variable None Rarely untreated Standard Variable
Epoxy resins (Opticon) 1.545± Increases Methylene chloride High and growing (highly toxic & carcinogenic) growing Difficult. Confused with oil treatment. Excellent short term. Long-term unknown. Possible damage by heat. Ultrasonic OK.
Palm oil (synthetic resin) 1.570- 1.572 Does not affect Acetone Alcohols High Confused with Opticon Excellent short-term. Turns milky long-term.
Cedarwood 1.500- 1.510 Does not affect Acetone Alcohols High Easily with training Removed by solvent, heat, ultrasonic.
Canada balsam 1.530- 1.550 Does not affect Acetone Alcohols Medium Easily with training Removed by solvent, heat ultrasonic.
Other oils 1.400-1.550 Does not affect Acetone Alcohols Low Easily with training Removed by solvent, heat,

Labs will note on reports that filling exists, but they prefer not to identify the type of filling. It’s difficult to make such distinctions, and the expense may not be justified.

While emeralds have drawn the most attention, other gems also are treated with epoxy resin. Among them are tourmaline, spinel, garnet, amethyst, chrysoberyl and aquamarine, as well as opaque gems such as jadeite and turquoise. Techniques for detecting epoxy fillings in emerald may not apply even to other transparent gems because of differences in refractive index or degree of transparency.


Selling every colored gemstone with a certificate to confirm that it’s natural and untreated may sound like a radical and expensive approach. But Osnat Gad at O.G. Gems, New York, N.Y., sees it as insurance.

“We import precious stones from all over the world, and we don’t want to find out later a stone is partially glass, glass-filled or synthetic,” says Gad. A certificate offers the peace of mind the gems are what they’re purported to be.

Gad trusts her suppliers to sell her untreated gems. Still, as soon as she gets them, they’re off to an independent lab for testing. If there’s evidence of traditional treatment (such as heating in sapphire), Gad discloses that information to the buyer. But every gem that is natural gets a full certificate confirming that fact. O.G. Gems also includes information about the gem’s origin on the certificate.

This has become important, she says, as more and more unscrupulous dealers indicate origin as a confirmation of pedigree while hiding the fact the gem may be heavily treated. Gad points to rubies as an example. Rubies from the Mong Hsu deposit in Myanmar are said to be almost 100% heat-treated. As part of the treatment, fractures or voids are partially filled with glass-like substances, making the gem look far better. This is where deception may occur; if the treatment isn’t disclosed, the buyer may think he or she has a far better gem than reality dictates. Fine untreated rubies from Mogok are considered the standard by which all others are judged, and Gad feels it’s unfair to lump lesser-quality “Burmese rubies” under the same pedigree.

Gad says she is a pioneer of this approach. While gem dealers occasionally get reports for gems they feel dubious about, Gad sends all her gems to the American Gemological Laboratories in New York, N.Y. Gad says she’s been able to absorb the cost of the reports in other areas of her business.


U.S. importers of South Sea and black cultured pearls from French Polynesia, Indonesia and the Cook Islands no longer pay an import duty.

The three countries were designated as “beneficiary developing countries” under the Generalized System of Preferences, part of the Trade Act of 1974. The GSP granted duty-free entry to these designated countries’ products, including the white, yellow and black pearls of Indonesia and the Cook Islands and the Tahitian black pearls of French Polynesia.

However, the U.S. Congress failed to renew the GSP when it expired in July 1995, and importers of cultured pearls from GSP countries paid a 2.5% import tax until August 1996, when Congress reinstated duty-free status.

Importers may request retroactive reimbursement for customs taxes paid between Sept. 1, 1995, and Aug. 31, 1996, by writing to U.S. Customs – Protest Section, Room 761, Six World Trade Center, New York, NY 10048.

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