New York–American Gemological Laboratories (AGL) is modifying the disclosure terminology it uses for treated rubies by exchanging the term “inorganic (fluxtype)” with “heating residues” in its descriptions of heat-treated rubies, the lab announced.
In a statement issued on Wednesday, the lab also said it would be including the statement “Heating residues are deposited along healed fractures during the heating process” as an additional description under the comments section of all grading reports for rubies.
The way in which the healing of fissures during the heating process of rubies has been handled has been a contentious topic for more than a decade.
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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.
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From: G&G Brief 6 October 2009
Intensely colored pink and red diamonds are very rare in nature. As a result, various methods have been developed to induce or enhance these colors in natural diamonds. GIA’s New York lab recently examined a large (8.44 ct) Fancy Vivid orangy pink pear shape submitted for grading that was found to have had its color introduced by a relatively new treatment. This diamond showed an even color distribution and was internally clean. Spectroscopic analysis revealed a very low concentration of aggregated B-form nitrogen and trace amounts of isolated nitrogen. Strong absorptions from NV centers at 575.0 and 637.0 nm were the main cause of the treated-pink color. Also observed in the UV-Vis-NIR spectra were moderate absorptions from the ND1, H3, H4, 594, and GR1 defects. All the observations strongly indicated that the treatment process involved HPHT annealing and subsequent irradiation and annealing at relatively low temperatures.
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