The World Jewellery Confederation (CIBJO) has released its sixth gemstone special report ahead of the 2017 CIBJO Congress in Bangkok, Thailand, on November 5.
According to Gem Konnect, the report, prepared by Dr. Hanco Zwaan, President of CIBJO’s Gemmology Commission, looks at guidelines for color terms like “royal blue” and “pigeon blood red”, as well as concerns about failure to include undetected treatments in gemstones in lab reports.
According to Zwaan, “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”.
As for colors defined as “royal blue” or “pigeon blood red”, CIBJO claims that there is an agreement by which laboratories will assign these descriptive colours only for “very well saturated colours, within strict limits of hue and tone”. However, “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”.
