Fluorescence
A diamond's tendency to emit visible light (usually blue) when exposed to UV radiation.
Definition
Fluorescence describes a diamond's ability to emit visible light — most commonly blue — when exposed to ultraviolet (UV) radiation such as sunlight or blacklights. The GIA grades fluorescence as None, Faint, Medium, Strong, or Very Strong. Blue fluorescence occurs in approximately 25–35% of gem-quality diamonds. In rare cases, strong fluorescence can make a diamond appear milky or hazy, reducing its appeal.
Why It Matters for Ring Design
Strong blue fluorescence can be a value opportunity: I, J, and K color diamonds with blue fluorescence often appear whiter in daylight (which contains UV) than their color grade suggests, and they typically sell at a 5–15% discount compared to non-fluorescent stones of the same grade. This is worth explaining to budget-conscious clients.
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