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Fluoresence in Diamonds

Fluorescence in Diamonds, some people like the effect while others do not, in usual circumstances it is never seen unless the diamond displays a very high fluorescence, though if a diamond that displays usual fluorescence is exposed to direct or intense ultraviolet light a bluish glow can be observed. Strong fluorescence can lower the price of a Diamond, but in some case may even lift the color one grade to the naked eye so to add to the beauty, or even detract from the diamond giving it a slightly hazy appearance. It's one factor that should be check with the individual opinion depending on the amount of fluorescence displayed.

Listed below are the abbreviations for describing strength of fluorescence that should be noted when reading a diamond grading report:

• N, NO, NON, - No Fluorescence
• F, FB, FT, FA, - Faint or Faint Blue Fluorescence
• SL, SLB, SLT, - Slight Fluorescence
• M, MO, ME, MD - Medium or Moderate Fluorescence
• S, ST, STB, STG, - Strong Fluorescence
• E, EX, EXB, EF, - Extreme Fluorescence

A contribution to understanding the effect of blue fluorescence on the appearance of diamonds

By Thomas M. Moses, Ilene M. Reinitz, Mary L. Johnson, John M. King, and James E. Shigley

Some gem diamonds fluoresce, most commonly blue, to the concentrated long-wave ultraviolet radiation of a UV lamp. There is a perception in the trade that this fluorescence has a negative effect on the overall appearance of such a diamond. Visual observation experiments were conducted to study this relationship. Four sets of very similar round brilliant diamonds, covering the color range from colorless to faint yellow, were selected for the different commonly encountered strengths of blue fluorescence they represented. These diamonds were then observed by trained graders, trade professionals, and average observers in various stone positions and lighting environments. For the average observer, meant to represent the jewelry buying public, no systematic effects of fluorescence were detected. Even the experienced observers did not consistently agree on the effects of fluorescence from one stone to the next. In general, the results revealed that strongly blue fluorescent diamonds were perceived to have a better color appearance when viewed table-up, with no discernible trend table-down. Most observers saw no relationship between fluorescence and transparency.

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