The Gemological Institute of America Laboratory reported that a significant
number of large high-pressure/high-temperature-treated color diamonds were
recently submitted for grading.
Ranging from 3 carats to nearly 20 carats, the vast majority of these stones were
submitted without full disclosure. The color grades ranged from “D” to “J”, but
most were “G” or better combined with high clarities.
“The range of diamonds being subjected to the treatment has also expanded,”
said Tom Moses, senior vice president of the GIA Laboratory and Research, in
statement. “We are confident that we can identify virtually all these treated
diamonds as a result of our extensive research in this area, which is one of
the most important initiatives at GIA. However, we do not know if this recent
surge in treated stones represents a new source or an attempt by some clients
to ‘test the systems’ at GIA.”
According to Moses, GIA is contacting the clients both to learn the source of
the treated diamonds and to remind them that the failure to disclose treatment
at all stages of the pipeline is unacceptable. In addition, GIA is reviewing
each transaction to determine whether it’s appropriate to turn over relevant
information to the trade organizations and law enforcement bodies.