Diny’s Jewelers


Fluorescence in Diamonds

What is diamond fluorescence? Is it good or bad? Should you buy (or not buy) a diamond because of it?

We want to help you answer the most frequently asked questions about diamond fluorescence to help you the diamond that is perfect for you.

  1. What is diamond fluorescence?

Fluorescence is the faint glow you sometimes see when a diamond is exposed to ultraviolet (UV) rays from sources like the sun and fluorescent lamps, such as a black light. This causes them to emit a bluish light and on rare cases a yellow or orangy light when a diamond does posses fluorescence.

  1. Do all diamonds fluoresce?

No. Experts believe that only about 25% to 35% of diamonds exhibit some degree of fluorescence.

  1. Is there a diamond fluorescence grade?

Diamond fluorescence is considered an identifying characteristic. It is not a grading factor.  Diamond Grading Reports describe a diamond’s fluorescence by its intensity. If the glow is Medium, Strong, or Very Strong intensity, the color of the fluorescence will be noted. But overall it has very little to no affect on the value of a diamond.

black light diamonds

Copyright: GIA and Harold & Erica Van Pelt. Courtesy: Harry Winston, Inc.

 4. Can an average person tell the difference between diamonds that do and don’t fluoresce?

GIA has studied the effect on diamond appearance.  Here is what they found: “For the average observer, meant to represent the jewelry buying public, no systematic effects of blue fluorescence on the face-up appearance of the groups of diamonds were detected. Even experienced observers did not consistently agree on the effects of fluorescence from one stone to the next.”

Which really just means that it has a negligible effect on the appearance of diamonds in the colorless or near-colorless grade ranges except for a slight improvement in the rare instances of very strong intensity in a diamond.

Fluorescence in diamonds black light

On the left, a group of seven diamonds under daylight-equivalent illumination. On the right, the same diamonds under long-wave UV illumination.

Photo: Kevin Schumacher/GIA

  1. Is diamond fluorescence good or bad?

It is neither a good or a bad thing. A diamond’s beauty is in the eye of the beholder. You may notice it, or you may not. It is just a neat affect that some stones have under black light, which you may or may not be drawn to.

Perhaps diamond fluorescence sparks so much conversation because its effect is so subjective.  See if you notice it the next time you’re in Diny’s Jewelers. As always you should love what you end up buying. There’s no hard rule, so let your heart lead the way.




Main Image Copyright: GIA and Harold & Erica Van Pelt. Courtesy: Harry Winston, Inc.


Categories:   Diamonds Delight, Jewelry News


Sorry, comments are closed for this item.