Numerous sapphires coming out of Bangkok have been diffusion treated to give the appearance of a nice padparadschas, according to recently released findings by the American Gem Trade Association Testing Center.
“They’re Madagascar pink sapphires being diffused with oxygen, and quite possibly something else, giving them a distinctly orangey appearance,” Kenneth Scarratt, AGTA director, said of the findings.
On a visit to Bangkok in November and December last year, Scarratt asked two separate dealers to send some samples to the laboratory for testing. “Every stone looked at immersed in methylene iodide against a diffuser plate shows a distinct rim of orange color around the stone,” Scarratt said. This is not the same appearance shown by blue diffusion treated sapphires, which display an apparent color concentration at facet junctions.
“This so far has not been seen in these `padparadschas,'” says Scarratt. Most of the sapphires in for testing were approximately .5 cts., but there are larger sapphires, up to 4 cts., that have been treated.
Scarratt notes that buyers of this type of material should immerse these stones in a liquid such as methylene iodide, and with the aid of a diffuser plate, look for any orange and pink color concentrations. If orange color concentrations appear to form a rim that follows the three-dimensional outline of the gemstone, seek further advice from a gem laboratory, he said.
To contact the AGTA-GTC, call Ken Scarratt at (212) 752-1717, or e-mail; firstname.lastname@example.org