What is Diamond Fluorescence?

Diamonds with fluorescence emit a soft glow under UV light, much like a white shirt under a “black” light.

You may save money on a diamond with faint to medium blue fluorescence, H color or below. This diamond may appear whiter. To avoid a hazy looking diamond, select faint blue or no fluorescence with a G color or higher.

We recommend you view your diamond in person under optimal lighting before your purchase.

Diamond fluorescence, from none to very strong under long wave uv light

GIA diamond fluorescence study

Diamond fluorescence is hotly debated in the diamond industry. But a Gemological Institute of America study suggested that fluorescence makes very little difference in a diamond's appearance. Most consumers can not see a difference between diamonds that do and do not fluoresce, with certain important exceptions, described below. Here’s an excerpt from the GIA study:

" . . . the results revealed that strongly blue fluorescent diamonds were perceived to have a better color appearance when viewed table-up [ed: right-side up, as when placed in a setting] . . . Most observers saw no relationship between fluorescence and transparency."

GIA Report of a round brilliant cut diamond with J color and strong blue fluorescence.

Fluorescence grading

About one-third of all gem-quality diamonds fluoresce, and near all fluoresce in a blue color. GIA grades fluorescence as inert, faint, negligible, medium, strong and very strong. Medium or lower diamond fluorescence grades can usually only be detected by a gemologist.

Diamonds with strong fluorescence often appear hazy in regular light, affecting the beauty of your diamond. This is especially true of diamonds with a better color grades (approximately G or above).

Fluorescence affects diamonds with a lower color (approximately H or below) very differently. Fluorescence may make the diamond appear to have less of a yellow tint, making the diamond look better.


"Came here for my fiancées wedding ring, and left a forever customer. Everyone goes above and beyond for their clients. If you're looking for exceptional quality and superior customer service, Fox Fine Jewelry is the place you need to shop."

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A loose diamond showing very strong blue fluorescence.

How diamonds fluorescence affects price

Often diamond prices aren't fully adjusted for the effects of fluorescence. Instead, pricing can prioritize gemological reports – which give limited information - over a diamond’s beauty. Therefore, there are opportunities if one chooses carefully.

The sweet spot can be a diamond with medium or strong fluorescence in a higher color grade, discounted for these factors. If the diamond is unaffected by the fluorescence, it may be spectacular.

It is best to view fluorescent diamonds in person under correct lighting, as the appearance varies from diamond to diamond.

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