Discuss Elle's answer to: Will fluorescence in diamonds impact beauty?

Fluorescence can enhance or detract from the beauty of a diamond. The bluish tint can improve a lower-color diamond (J-M color rated) by cancelling out the faint yellow, resulting in a colorless appearance. However, in a very high-color diamond (D-F color rated), fluorescence may have the opposite effect.

In a small number of diamonds, the presence of strong fluorescence creates a hazy, milky, oily, or cloudy appearance. For this reason, very fluorescent diamonds can be valued lower than similar diamonds with fluorescent ratings of "None," "Faint," or "Medium." If you have selected a diamond with "Strong" or "Very Strong" fluorescence.

Source: Brilliance.com