Fluorescence is the effect that ultraviolet (UV) light has on a diamond. Some diamonds have fluorescent properties that cause the diamond to glow under UV lights. The glow is usually blue, but sometimes the diamond can also release shades of green, yellow, pink, orange, and red. Under most lighting conditions, a diamond's fluorescence is not visible to the naked eye. Not all diamonds have fluoresce. If a specific diamond doesn't, the grading report will list the diamond's fluorescence as none. Fluorescence is a naturally occurring phenomenon that appears in certain minerals and gems. Fluorescence can occur in different intensities. Gemological laboratories rate the fluorescence of each diamond on a scale from "None" to "Very Strong". Diamonds with a strong or very strong fluorescence are a better value since their market prices is slightly lower than diamonds with faint or negligible fluorescence.
No fluorescence, no influence on color
Weak fluorescence, slight glow that is difficult to see under ultraviolet light, not a significant influence on color.
Average fluorescence, small influence
Strong influence, substantial color influence
Very strong influence, the diamond emits a deep glow that is very clear under ultraviolet light.
The Fluorescence Effect
Fluorescence usually has no effect on a diamond's appearance in regular light conditions. In some cases strong blue fluorescence can make a yellow colored diamond appear whiter, but in rare cases it can cause a stone to appear milky or oily. If you have selected a diamond with "Strong" or "Very Strong" fluorescence, please contact our diamond expert and jewelry consultants to have it visually inspected before purchasing.