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CIBJO Recommends Certificates State Some Treatments Can’t Be Detected

The World Jewellery Confederation CIBJO has released its sixth gemstone special report that looks at a series of issues on the agenda of the gemmological community, including guidelines for colour terms like "royal blue" and "pigeon blood red," and the way in which possible undetermined treatments can be explained on laboratory reports.

The report, prepared by Dr. Hanco Zwaan, President of CIBJO's Gemmology Commission, has come out just weeks before the opening of the 2017 CIBJO Congress in Bangkok, Thailand, on November 5.

Concerns have been raised about laboratory reports that fail to include comments when gemstone treatments cannot be detected — as is the case with heat treated aquamarines and irradiated tourmalines. "A person reading the report may consider that the lack of information provided implies that the stone is not treated, rather than communicating that there may have been a treatment that is undetected," Zwaan writes.

To address the issue, the newest draft of CIBJO's Gemstone Blue Book proposes that laboratories note on reports that an absence or lack of comments in the treatment section of a laboratory report does not necessarily mean that the stone has not been subject to a treatment, for there are treatments that currently cannot be definitively proven to exist. The statement could be followed by a list of undetectable treatments.

The special report also describes progress that was made under CIBJO's auspices toward harmonising the standards by which laboratories will assign descriptive colour terms like "royal blue" and "pigeon blood red." There is agreement that only very well saturated colours, within strict limits of hue and tone, are eligible to receive the specific colour terms, but disagreement still remains as to the degree of fluorescence necessary for the terms to be awarded, and even whether or not fluorescence should be taken into account at all.

"Additional steps that need to be taken on this issue will be discussed at the 2017 CIBJO Congress in Bangkok, and hopefully progress will be made, “Zwaan writes.

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