The American Gem Trade Asociation’s Gem Testing Center laboratory (AGTA GTC) will issue standard heat treatment identification reports for the blue sapphires with unusual color distribution.
Working in concert with the Gemological Institute of America (GIA) and others, the AGTA lab has been investigating the cause of the unusual color distribution seen in numerous blue sapphires that have been heated in Sri Lanka (see www.agta.org/consumer/gtclab/index.htm).
On Friday April 2 most members of The “Corundum Research Group,” made up of Prof. George Rossman, Dr. John Emmett, Troy Douthit (AGTA), Shane McClure (GTL), Christopher Smith (GTL), Dr. Mary Johnson (GTL), Mathew Hall (GTL), Dr. Wuyi Wang (GTL), Dr. Andy Shen, Dr. Michael Breeding, John Koivula (GTL), Ken Scarratt (AGTA), Tom Moses (GTL), Garry Du Toit (AGTA) and Donna Beaton, met to discuss these blue sapphires. This meeting followed two trips to Sri Lanka to assess the heating procedures used to produce this unusual color distribution, research into the type of material that is being used, and detailed chemical as well as IR analyses of the treated stones.
As it was announced earlier in the GIA pres release, they concluded that the color distribution is the product of the specific heating regimen used by gemstone treaters in Sri Lanka. Further, they found no evidence of intentional or inadvertent diffusion of elements.
Therefore AGTA-GTC shall use the standard disclosure terminology for heat treatment to describe these stones on reports – “indications of heating.”