On May 4 and 5, 2002, representatives of four gemological laboratories, along with two noted scientists, met to discuss the results and ramifications of research into the recent treatment applied to sapphires and rubies in Thailand.  Hosted by the Gemological Institute of America, representatives of the GIA Gem Trade Laboratory, AGTA Gem Testing Center, Gemological Institute of Thailand, and SSEF Swiss Gemmological Institute met in Carlsbad, California, with Dr. John Emmett, president of Crystal Chemistry in Brush Prairie, Washington, and Dr. George Rossman, professor of mineralogy at the California Institute of Technology in Pasadena, California.

The meeting concluded with recommendations concerning the terminology used to describe corundum treated by this new technique. While discussions among other laboratories are ongoing, the GIA Gem Trade Laboratory and AGTA Gem Testing Center, based on the discussions and recommendations at this meeting, as well as on the research conducted to date by GIA and AGTA, are changing their reporting policies for the new corundum treatments effective immediately. These policies pertain mainly to yellow, orange, orange-pink, and orangy red colors of corundum. Blue sapphires are not significantly affected. The new wording reflects two significant determinations with regard to these treatments:  (1) that they involve bulk diffusion, and (2) that an overgrowth of synthetic material has been observed on several stones. Each is explained below, and the new wording is indicated.

1. The induced color, whether present as a rim close to the surface, or continuing throughout the stone, is caused by a process known as bulk diffusion.  As a result of these discussions and a review of the technical literature, it is clear that “bulk diffusion” is scientifically correct and should replace the terms “surface diffusion” and “diffusion treated” as they were previously used gemologically. GIA and AGTA reports on such stones will include wording similar to the following (to be adjusted per the specific format of each lab’s report):

2. Overgrowth of synthetic material occurs during the new treatment process. If such a synthetic overgrowth is still present on the finished stone, it will be addressed in the identification report as follows, again with adjustments per the individual report format:

At this time, the above policies and revised wording apply only to GIA and AGTA lab reports.

May 29, 2002