Overgrading Blue Fluorescent Diamonds, the problem, the proof and the solutions

Long after worldwide acceptance of the GIA-established standard of UV-free, daylight-colour-balanced illumination for the correct colour grading of a diamond's “true body colour”, an examination of diamond trade and laboratory grading practices finds nearly everyone, including GIA, employing some type of fluorescent tube lighting. GIA taught that this lighting “causes fluorescent diamonds to be graded higher than is actually warranted due to the neutralizing, or masking, effect of the fluorescent color on the true body color". This work demonstrates the over grading of blue-fluorescent diamonds that often results, and which adds to the distrust of strongly fluorescent diamonds and their resulting discounting at the wholesale level. Three methods to resolve this problem are proposed which, by themselves or in combination, provide inexpensive and workable solutions. New lighting standards are proposed that would insure a return to color grading of a diamond‘s “true body color“.