The international controversy that developed on suspected treatment techniques by a Sri Lankan Heat Treater has been concluded clearing all doubts. One of the world's reputed leading gemological laboratories, GIA has affirmed that they have found no evidence of intentional or inadvertent diffusion of elements from an outside source that would require special disclosure on their gemological reports, said Chairman, National Gem and Jewellery Authority (NGJA) Tennekone Rusiripala.

When in early 2003 gemologists from the Gemological Institute of America and American Gem Testing Association laboratories first noticed unusual colour concentrations in heat-treated blue sapphires coming from Sri Lanka, they were concerned that it might be a new form of treatment similar to what was detected in Bangkok, Thailand the previous year. In response they launched an intensive research project that involved highly advanced analytical techniques.

Rusiripala said the National Gem and Jewellery Authority on its part got involved in the matter directly and provided all assistance required by the gemologists who teamed up as a group from several leading gem labs in the world.

One of the serious concerns of the leading laboratories was how the labs consider and disclose heat treatment on their corundum reports.

Hundreds of non-heated and heated blue sapphires were involved in their research including several types of Geuda, the colourless to white or pale-blue starting material. Numerous tests were conducted to compare the inner-blue colour concentrations and the outer decolorised regions of the suspected stones, he said.

It is reported that these included several advance tests and hundreds of highly sensitive chemical analysis.

During the course of two research trips to Sri Lanka the team of gemologists investigated the specific heating process and more than 20 samples were analysed to document the changes that took place.

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