This happened last week:
"GIA reasonably suspects that approximately 500 colorless to near colorless diamonds submitted primarily to our laboratory in Israel potentially were subjected to an undisclosed temporary treatment.
GIA believes that the treatment is a process that temporarily masks the inherent color of the diamond and can lead to a higher grade. The color difference can be as much as three grades. GIA has not yet identified the treatment process, but this is being actively researched. At this time, the diamonds treated in this way have been submitted by just a few clients. "
The full article can be accessed here: http://www.gia.edu/gem-lab/laboratory-alert-may-2015
"GIA reasonably suspects that approximately 500 colorless to near colorless diamonds submitted primarily to our laboratory in Israel potentially were subjected to an undisclosed temporary treatment.
GIA believes that the treatment is a process that temporarily masks the inherent color of the diamond and can lead to a higher grade. The color difference can be as much as three grades. GIA has not yet identified the treatment process, but this is being actively researched. At this time, the diamonds treated in this way have been submitted by just a few clients. "
The full article can be accessed here: http://www.gia.edu/gem-lab/laboratory-alert-may-2015
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