You may have come across the term fluorescence on a diamond grading report from the GIA, SGL or any other grading authority. Most people who purchase diamonds may not care about fluorescence, but if you’re one of the few who is confused by the term, it simply refers to the effects diamonds display under ultraviolet light.

In the simplest terms, diamond fluorescence is the effect that UV light has on a diamond. Similar to how whites get brighter and your teeth appear to glow, a diamond emits a visible fluorescent light when it is exposed to UV light.

Based on information collected by the Gemological Institute of America, “the strength of fluorescence has no widely noticeable effect on appearance. In the GIA Fluorescence Study, it was found that the average person could not make a distinction between a diamond with fluorescence and a diamond without”

Often observers prefer the appearance of diamonds that possess medium to strong fluorescence. Very rarely do some diamonds with extremely strong fluorescence appear hazy or oily.

Fluorescence has no effect on the structural integrity of the diamond. However, the preference to buy one that exhibits fluorescence is a personal one since the diamond’s appearance should be taken as a whole.

Source: GIA