The American Gem Trade Association Gemological Testing Center (AGTA GTC) has released preliminary data on heated blue sapphires with an unusual color distribution that at this time has been treated in a way that the lab cannot identify.
Until the AGTA GTC can identify the treatment of these sapphires, it will not issue reports on these stones, the organization said in a statement. In addition, the team of researchers who carried the study said the, “The number of stones observed with these characteristics now increases daily.”
The researchers say the sapphires have a “light [pastel] blue to near colorless rim surrounded by a deep blue color. Viewed in various directions, the boundary between the central blue color and the outer rim could be seen to be undulating.”
Identifying the sapphires is reasonably simple using “gemological techniques,” researchers say. “The most common technique is to immerse the gemstone in methylene iodide to observe a blue core surrounded by a colorless or near colorless outer rim.” However, the treatment of these sapphires remains a mystery.
“The research team is working diligently to gain a clearer picture of the process,” the statement said. “In the meantime, it is inappropriate to speculate beyond stating that this process does not appear to be one that we can recognize as being ‘normal heat treatment’ and, as no beryllium has thus far been found, it does not appear to be a process involving the diffusion of beryllium.”
The organization adds that it will continue to issue reports on sapphires (heated or unheated) that show no indications of being treated by the unidentified process.
The lab has implemented a batch testing service to assist the trade in separating these stones from other heat-treated blue sapphires.
“It should be reiterated that while we are continuing our research to fully understand the treatment process these sapphires have been subjected to, it is a reasonably simple gemological process to identify the sapphires that have been treated in this fashion. Stones submitted in batches will be separated into those that show the characteristics described here and those that do not.”
The fee for the batch testing service is $300 per hour with a half-hour minimum. Fees for consultation on these gemstones is $400 per hour with a quarter-hour minimum.
The gemological team carrying out this investigation consists of AGTA and GIA staff members and advisors including John Emmett, George Rossman, Kenneth Scarratt, Garry DuToit, Donna Beaton, Tom Moses, Shane McClure, John Koivula, Christopher Smith, Mary Johnson, Matthew Hall, Wuyi Wang, and James Shigley.
More details of the identification can be found at www.agta.org under “Breaking News.”