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AGTA GTC issues alert on dyed tourmaline

February 25, 2009

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New York--The American Gem Trade Association Gemological Testing Center (AGTA GTC) has issued a lab update regarding dyed tourmaline.

Recently, the lab was given a pink necklace for identification that was composed of small rough beads, approximately 5 millimeters by 4 millimeters by 2 millimeters in size.

According to the AGTA GTC, a first look in the microscope showed that the gemstones were natural but dyed, and that they were not, as expected, corundum or quartz. Instead, chemical analysis led to the conclusion that the material was tourmaline.

A closer investigation showed that the pink/red material was concentrated on the surface, in fractures and, in rare occasions, in the tubes typical of tourmaline.

With this recent discovery, the AGTA GTC has now added tourmaline to the list of dyed materials that includes corundum and members of the quartz family.

Back in November, the AGTA GTC issued a similar update on dyed corundum, when small beads in red, green and blue showed a chemistry consistent with corundum as well as typical corundum peaks together with peaks from artificial dyes on the Raman spectrum.

In other AGTA GTC news, the center will be offering advanced, hands-on seminars for corundum and emerald treatments from March 5-6.

Participants will learn how gemological laboratories detect and describe such   treatments. In addition, the sessions will offer a brief review of the major treatment technologies as well as the AGTA GTC's Gemstone Report nomenclature. This will be followed by a laboratory session, where participants personally examine samples, concentrating on separation of untreated corundum (NTE) from the following treated rubies and sapphires:

--Heat (TE)
--Flux healing (TE1 to TE5)
--Glass cavity filling (C1 to C3)
--Glass fracture filling (F1 to F3)
--Oils, dyes and irradiation

The emerald lab session covers the separation of untreated emerald, emerald   with clarity enhancements, plus a microscopic evaluation of filler types.

The seminars will be held from 9:30 a.m.-12:30 p.m., with a one-hour break for lunch, followed by the afternoon session from 1:30 p.m-4:30 p.m., at the AGTA Gemological Testing Center, 18 E. 48th St., Ste. 502, New York, NY 10017.

For seminar fees and special offers, contact Jason Harmon at (212) 752-1717.

For more information about the AGTA GTC, visit its Web site, AGTA-GTC.org.
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