Understanding Diamond Fluorescence and How To Take Advantage of It

Understanding Diamond Fluorescence and How To Take Advantage of It


When subjected to ultraviolet light, about one third of diamonds will exhibit fluorescence. That is, a soft, colored glow, similar to what might happen to a white t-shirt in a nightclub with a black light, or at a glow-in-the-dark bowling alley. Most of the time the fluorescent color is blue, though yellow, orange and white are also possible. Fluorescence is graded on a scale from None to Very Strong.

Image courtesy of GIA

Why retailers don’t like fluorescence

There tends to be a consumer bias against fluorescence, which can be frustrating for retailers. It is seen as a flaw in the stone, thus customers believe they are overpaying. What much of the general public doesn’t realize is that in many cases, fluorescence actually improves a diamond’s appearance.

The Gemological Institute of America (GIA) has stated in Gems and Gemology that typically, fluorescence is a positive attribute in diamonds. This view is shared by many industry professionals.

Fluorescence can only be seen in ultraviolet light. It is most noticeable under a black light, and will be visible, to varying degrees, in every fluorescence grade except None. The fluorescence grades Fair and Medium will not impact the appearance of a stone, except under black light. Strong and Very Strong fluorescence will affect the appearance of a stone under normal light.

In a diamond with a low color grade, fluorescence is actually desirable. The soft blue color will balance the yellow tint, making the stone appear brighter and whiter. This is because blue and yellow are complementary colors to one another in the color wheel. In diamonds with high color grades, high fluorescence might cause the stone to appear cloudy or milky. These stones will generally be offered at a discounted price.


How to take advantage of fluorescence when buying a diamond

There are various ways for customers to benefit from fluorescence when purchasing a diamond, depending on their budget and personal tastes.

A diamond with a low color grade and a high fluorescence grade can be an excellent bargain. The fluorescence grade will change the appearance of the stone, but will do so by making it appear whiter or colorless, thus disguising its yellow tint. This could make a stone appear one or two color grades above what it actually is. And of course, it would be priced at the lower color grade.

If a colorless diamond (D to F grade) has any fluorescence grade, it will be offered at a discounted rate. As already mentioned, choosing a diamond that also has high fluorescence could mean choosing a diamond that has a visible haze or cloudy. The best way is to use a visual loop and see if it is cloudy. If you are buying the diamond online, you want to verify with the stone owner what their opinion is on the haze or cloudiness if the diamond has  strong fluorescence.

However, this is not the case with Faint or Medium grades. Choosing a diamond with a high color and low fluorescence grade is an excellent way to save some money while still getting a high quality diamond.

For some people, choosing a diamond with high color and fluorescence grades is the right choice. Years ago, “blue-white” diamonds were actually in style, and highly sought out. Some people appreciate the novelty of these diamonds, and enjoy the effects on them under certain light. In this case, it’s a matter of personal taste.

Frank Fisher

Author: Frank Fisher

Frank Fisher (Sasha Evdakov) started learning about diamonds at a young age through his cultural background and family influence. He spent years being mentored by the best diamond dealers and has been studying diamonds and the diamond market since 1998.
  • newbie

    What if I am looking for a fancy yellow diamond n its stated as medium blue fluorescence ? does it makes the fancy yellow looks more white then? Thank you

    • It depends on the lighting condition you look at. If you look at a medium fluorescence diamond in a black light environment then it will stand out and can give it a shiny blue glow…

      If you are looking for a whiter diamond which is color – then you should just get a better color diamond rather than compensating with the fluorescence.

  • Joy

    So if my ring under a black light glows ” very strong” is that good or bad? Because my husband just bought me this wedding band last month.

    • It depends on the lighting conditions and when you look at the stone (outside versus night club). Normally most people do not like florescence and it is not desirable since fluorescence makes a diamond glow. This can make it appear unnatural. It does not mean it is a fake diamond. It doesn’t mean it is bad or good, just in certain lighting conditions it make not be desirable. Ask yourself how often you go to a night club

      • Joy

        It looks very weird too, At the club it was only 2 stones that were glowing but when we tried it at home all the diamonds glowed. We turned off the lights in our bedroom when we did it with the black light. I’m thinking I’m gonna just gonna take the ring back b/c this scares me. I don’t want glowing diamonds. We go to the club quite often and I’ve never had diamonds glow lol. My husband paid a lot of money for this wedding band. Thanks for the information!!!

        • Well there is nothing to be afraid of. But if you don’t want glowing diamonds, then you want to look for diamonds with Fluorescence: NONE. Diamond purchasing can be tricky since its an area most people do not know much about. Read some of my other articles and learn more information before getting a replacement.

          • Joy

            I’ll do that thank u. Yea I’ve never heard or seen this before this, and I’ve got tons of diamonds!

          • Joy

            also where could I find more of your articles?

          • Just look at findmyrock.com website – 90% of the stuff on here is my stuff.