Gemstone Enhancement and Detection in the 1990s

Gemstone Enhancement and Its Detection in the 2000s

“…A nother decade has passed since we reviewed the events of the 1990s as they pertained to gemstone enhancements and their detection (McClure and Smith, 2000). At that time, we observed that the issue of disclosure (and, especially, the failure to disclose) had caused major upheaval in all areas of the jewelry industry.…”

“…By late 2000, more than 2,000 decolorized type IIa HPHT-treated diamonds had been seen at the GIA Laboratory (McClure and Smith, 2000). Today, with several treaters in various countries removing color from diamonds with HPHT annealing, this treatment has become almost commonplace.…”

“…Such features are not commonly observed in untreated colorless type IIa diamonds, although lightly pitted surfaces and graphitized or graphite inclusions have been seen on rare occasions. Therefore, such features are a good indication of treatment, but they are not proof by themselves (Moses et al, 1999;McClure and Smith, 2000;Gelb and Hall, 2002). Because these heat damage−related features are not always present in a faceted diamond or may be difficult to discern, detection of HPHT treatment in a type IIa diamond generally requires measurement of the absorption and/or photoluminescence (PL) spectra taken with the diamond cooled to a low temperature (see Chalain et al, 1999Chalain et al, , 2000Collins et al, 2000;De Weerdt and Van Royen, 2000;Fisher and Spits, 2000;Hänni et al, 2000;Smith et al, 2000;Collins, 2001Collins, , 2003Novikov et al, 2003;and Newton, 2006).…”

“…In the late 1990s, we began to see different colors of topaz (blue-to-green, orange, pink, and red) that were being represented as "diffused" (Fenelle, 1999;McClure and Smith, 2000). Schmetzer (2006Schmetzer ( , 2008 reviewed the patent literature and concluded that the various mechanisms and treatment methods were not diffusion and should all be described as "surface coated."…”

“…Building on previous reviews (Kammerling et al, 1990a;McClure and Smith, 2000;Smith and McClure, 2002), the aim of this article is to provide an overview of the treatments and identification challenges associated with them that were common during the first decade of the 2000s. The authors strongly recommend that readers familiarize themselves with the original references, as all the pertinent information cannot be presented in a review article.…”