Diamond Fluorescence

In the diamond industry, the existence of fluorescence in a diamond , has caused many debates and has, in many instances, influenced the pricing of diamonds. Fluorescence, the effect ultraviolet light has on a diamond, is an important consideration when selecting a diamond. When UV light strikes a diamond with fluorescent properties, the stone emits a glow that is usually blue, but can also reflect shades of green, yellow, white. The sources of fluorescence, boron and nitrogen, are the same mineral properties that lend color to a diamond.

Fluorescence can occur in different intensities. Gemological laboratories rate the fluorescence of each diamond on a scale from “None” to “Very Strong”.

None, Nil, Negligible

No fluorescence, no influence on color

Faint, Slight

Weak fluorescence, not a significant influence on color (barely perceptible)


Average fluorescence, small influence

Strong, Extremely Strong

Strong influence, substantial color influence

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Diamond Fluorescence

The Fluorescence Effect

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 very strong fluorescence creates a hazy, milky, oily, or cloudy.

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, please contact a JBE Diamonds diamond and jewelry expert to have it visually inspected before purchasing.