When consumers seeking for a diamond, which is H, I or J color, then medium fluorescence will make the stone look slightly whiter. If considering purchase a diamond with a G or higher color, then a diamond with either no fluorescence or faint fluorescence is recommended.

Diamond fluorescence, is the reaction of trace minerals within the diamond when exposed to UV lighting. Diamond fluorescence is a form of light releasing small amount of the energy obtained in the diamond. Around 50% of diamonds have fluorescence. The effect of diamond fluorescence ranking from “none” to “strong”, strong fluorescence can cause a diamond to look hazy, milky or less transparent. Because the fluorescent glow is usually blue fluorescence, as blue is the complementary color to yellow, blue fluorescence can make yellowish diamonds look white or colorless.

Gemological laboratories rate the fluorescence under ultraviolet (UV) light on a scale from ‘None’, ‘Faint’, ‘Medium’ to ‘Extremely Strong’. For a diamond with very high color (such as D-G grade), more than 50 points and clarity grade higher than VS, fluorescence has huge effect on the price. Medium fluorescence tend to affects the prices by 5%-10%, while strong fluorescence in the diamond with high color range (D-F) lead to a large price reduction up to 30% discount. Alternatively, a J color diamond of any clarity with medium fluorescence, the selling price will increase 2% compare to a diamond without fluorescence.