In the past several months, the GIA Gem Laboratory
has examined dozens of blue sapphires that showed
clear evidence of high-temperature heat treatment as well as unusual colour concentrations.
The stones have ranged from 1 to about 20 cts. The face-up appearance of these two 3-ct.
samples is representative of the material.


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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