In a recent addition to some of the GIA certs on the market a newly included paragraph on fluorescence is worth noting. It says: “GIA studies show that, for the overwhelming majority of diamonds, the strength of fluorescence, has no widely noticeable effect on appearance. In many instances, observers prefer the appearance of diamonds that have medium to strong fluorescence. In rare cases, some diamonds with extremely strong fluorescence may appear hazy or oily; fewer than 0.2% of the fluorescent diamonds submitted to the GIA exhibit this effect”
Does Fluorescence compromise the structural integrity of the diamond ?
“No. A diamond that fluoresces has the same integrity as one with no reaction to UV. Submicroscopic substitutions and/or shifts in the diamond structure can cause fluorescence as well as prevent it. Nothing in either in stance inherently weakens or is bad for the diamond”
Reference. Gemological Institute of America