Wednesday, April 04, 2007

Emerald Treatments

If you are not a gem or jewelry enthusiast, you may be surprised to learn that many gemstones are enhanced in some way or another. From diamonds, rubies, sapphires, and on down to 'lesser' stones, treatments are quite common. The types of treatments and the reasons for treating a stone are very dependent on the classification of the stone. Some estimates suggest up to 95-99% of all emeralds are treated. Most are treated to improve the passage of light within stone. The physical makeup of the emerald crystal, with its tiny natural fissures simply makes it logical to do so. As is the case with most gems, the stone's natural properties simply dictate which enhancements are acceptable and which are not. A perfect example of this would be the heat treatment of tanzanite. Before heating, tanzanite is a brownish color, but turns a permanent blue or purple color after heating. The enhancement method is accepted because no foreign coloring agents were introduced, the method is common practice, and it is generally fully disclosed to the buyer.

Cedarwood Oil

Many centuries ago, the Greeks began using colorless oils to improve the appearance of emeralds taken from Egypt. The oil would fill in the natural cracks and fissures within the stone improving how light may pass through the stone. The practice is still extremely common today. In fact, it is the most widely practiced and accepted method of emerald enhancement. Today, mostly natural, colorless cedar wood oil is used and has been for the past four decades. It is not permanent, but it is rather stable. Over time, some oil may gradually evaporate or 'leak' from the stone. When this happens to lightly oiled stones, the change in appearance will not be significant or even noticeable, but may be on those that are more heavily treated. Keep in mind that we are not talking about months or even a few years, but likely over a decade or more. Ultrasonic jewelry cleaners and harsh solvents will also remove cedar oil treatments and perhaps other types of treatments as well. These cleaners should never be used on emeralds. If a stone loses its oil enhancement, most can be retreated.

Epoxy

There are many types of epoxy treatments; therefore we will speak of them in a rather general sense. They are as varied as the emeralds they're applied to, and, of course, some are better than others. Epoxies are used to fill naturally, as well as unnaturally, occurring cracks and fissures in stones. They are used far less than cedar oil treatment and are considered a less desirable treatment option. The practice of using an epoxy is accepted to an extent. When done properly, the treatment can greatly improve the appearance and transparency of a stone. Some can be used to deceive the buyer..so you need to be aware of what's out there. From Embassy Emeralds you have little to worry about. Our sources are established and reputable. We feel very comfortable offering the stones we do because we know our sources share the same high quality standards that we do.

Gematrat

Gematrat was developed in 1997 as a way to permanently treat emeralds, leaving them in a stable and permanent state once finished. The process has been defined as 'gemstone branding' and begins with a very extensive cleaning of the stone which may take weeks or even months in some cases. The stone's tiny fissures and cracks are then filled with the colorless Gematrat substance, which is said not to leak or discolor. The substance also contains a tracer which glows blue under ultraviolet light.

According to the producers of the treatment, you can put Gematrat treated gems in an ultrasonic cleaner, a steamer, and even recut the stone without damage. The stones are marketed with an American Gemological Laboratories (AGL) report.

ExCel

Another emerald treatment process developed after the Gematrat process. This process does not include the tracer element that was present in the previous process because of incompatibilities with the treatment and the appearance of many fakes that mimicked the tracer's effect under ultraviolet light. Information about the gem is laser engraved on the girdle of the stone.

Palm Resin

Also known as Palma, this is a type of oil-like plastic treatment that is used in place of cedarwood oil. The treatment is not stable or permanent and tends to leave a milky-white residue. It is still used, but it is not considered an acceptable treatment.

Opticon

A plastic treatment that first appeared in Brazilian emeralds in the 1980's. The use of this treatment was not disclosed and was considered an unethical method of enhancement. The Opticon substance is green colored, but may turn yellowish over time. Many feel that Opticon treated emeralds are easily detected by their appearance when compared with typical untreated or cedarwood treated stones.

PermaSafe

This permanent, synthetic epoxy resin emerald treatment was developed by the Centro Gemologico para la Investigación de la Esmeralda (CGIE) in Bogota, Colombia. (Gemology Center for Emerald Investigation) The treatment was intended to be a Colombian alternative to the Gematrat and ExCel permanent treatments. It is reportedly a stable, permanent treatment that will not evaporate or leak and can safely be subjected to ultrasonic cleaning. The same resin has been used in other commercial applications outside of the jewelry industry.

Joban

A treatment commonly used in India that uses a green oil to not only fill and mask the cracks and fissures in the stone, but to also give it better color. The process is considered unethical.

Paraffin

Commonly used on African emeralds, paraffin is used in an oil or wax form.

0 Comments:

Post a Comment

<< Home