Corundum bulk diffusion treatment can be identified

Standard gemological testing procedures can be used to identify Corundum bulk diffusion treated sapphires coming from Asia, the Gemological Institute of America said today in a statement.

During the past several months there has been raging debate among gemstone dealers around the world over the classification, and identification and of color origin for these stones, which have been primarily coming from Thailand.

“It has been unequivocally established that the color change is caused by the diffusion of beryllium from an external source into the corundum,” GIA said in its statement. “Beryllium diffused into corundum, in an oxidizing atmosphere, at high temperatures, is the single causative agent of color change in this new process. Beryllium diffusion is very similar to the diffusion of titanium into corundum that creates a blue color layer, and thus both will be described similarly in our reports.”

GIA continues, “The primary effect of the beryllium diffusion is an added yellow color component, although other effects have also been observed. Depending on the starting material, the colors produced by this technique now present on the market are yellow, orange, orangy pink, orange-red, green, green-blue and violet.”

GIA says in its statement that it is now trying to establish identification criteria for these stones that are not identifiable by established testing methods. The method will include traditional and advanced analytical techniques.

“Establishment of these criteria is being given the highest priority at both the GIA Gem Trade Laboratory and the AGTA Gemological Testing Center, and we will be using all of the resources at our disposal, including consultation with outside experts,” the statement reads. “We believe these efforts will help allay the concerns of dealers and jewelers alike regarding this new treatment procedure, and will allow consumers to purchase corundum with certainty and confidence.”

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