Fluorescence is an intrisic property of a diamond displaying a natural blue fluorescence under any ultraviolet light. A strong blue fluorescence can give a "D" or "E" colored diamond a milky hue, but will help a lower colored diamond appear whiter.

Fluorescence will act as a neutralizer and any intrinsic yellow will be neutralized giving the diamond a whiter appearance. However, under UV light the diamond will illuminate with a bluish tint.