The CIBJO Gemmology Commission will discuss the question of how gemmological labs should present reports in cases when evidence of treatment is not definitive at the forthcoming Congress which will be held in Bangkok, Thailand, on November 5, 2017. The issue has been highlighted in the Commission’s Special Report, authored by Hanco Zwaan, its President, which is the sixth of the reports prepared by the different sectoral commissions for the Congress.

Among the series of issues on the agenda of the gemmological community, the report has focused on 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. It voices the concerns of many in the industry about laboratory reports that fail to include comments when gemstone treatments are "undeterminable," which can be the case with heat treated aquamarines and irradiated tourmalines.  

Dr. Zwaan writes, "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 undeterminable."

The newest draft of CIBJO's Gemstone Blue Book, which incorporates many of the points agreed upon at the previous Congress in Yerevan, Armenia, proposes that it should be mentioned in 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 Commission suggests. 

The Special Report also outlines some of the 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 disagree of fluorescence necessary for the terms to be awarded, and even whether or not fluorescence should be taken into account at all.

“The Congress will be discussing additional steps that need to be taken on this issue,” writes Dr. Zwaan.