The GIA, out of a statement from its HQ in Carlsbad has warned the trade that approximately 500 colourless to near-colourless diamonds submitted primarily to GIA’s grading laboratory in Ramat Gan, Israel, were “potentially subjected to an undisclosed temporary treatment”.

“GIA believes that the treatment temporarily masks the body colour of the diamond, resulting in a colour grade that can be up to three grades higher than its actual grade,” the laboratory stated. “The Institute has terminated client agreements with the companies that submitted the diamonds in question and has notified appropriate trade bodies.”

Further, GIA said that the report numbers of the “potentially treated stones” are posted on GIA’s website (http://www.gia.edu/gem-lab/laboratory-alert-may-2015).  It called upon anyone “who has purchased or has access to any of these diamonds... to submit them to any GIA lab for a no-cost, expedited review”.