Blue Fluorescence Effect (14.07)
Strong blue fluorescence will undoubtedly detract yellow in a diamond. Expect strong blue to hide several color grades in the mounting. It may look like a “G” in
the ring and if it turns out to be an “L” when loose on the grading tray, don’t be surprised. The easy solution to this potential problem is a simple check under longwave ultraviolet light. If it glows blue or a violet blue, you can expect a potential problem with grading. This is not to say that all strong blue-fluorescent diamonds are off color; in fact, many are in the colorless range.