Diamond Fluorescence

How Fluorescence Can Change Diamond Color

What Is Diamond Fluorescence?
A diamond factory employee examines a diamond. Paul O'Driscoll / Getty Images

What is Diamond Fluorescence?

Fluorescence is a characteristic that makes some diamonds appear to change color or glow when they are exposed to the ultraviolet light. Ultraviolet light can come in the form of either sunlight or by fluorescent lightbulbs. This change in color is completely different than a diamond's color

This glowing effect can be seen as either a negative or positive thing. A diamond's color can either enhance a diamond's natural color in sunlight or enhance the color under incandescent light (lightbulbs). However, the opposite can also be true. The fluorescence of a diamond can make a diamond appear more yellow that it actually is. This depends on the color the diamond emits as well as the type of lighting. 

Learn the basics of diamond fluorescence as well as why it's important to know whether or not your diamond glows under ultraviolet light. 

Do All Diamonds Fluoresce?

Not all diamonds have an intense fluorescence. Some don't show this quality at all. Diamond grading reports reveal whether or not a diamond fluoresces, and if it does, how much -- faintly, weakly, moderately, strongly or very strongly.

What Color is Visible in Diamond Fluorescence?

Diamond grading reports also disclose the color produced by a diamond's fluorescence -- it's usually blue, yellow or white. 

How Does Diamond Fluorescence Affect the Diamond

Be careful and always check a diamond grading report to check a diamond's fluorescence if possible. If a yellowish diamond fluoresces blue, the effect could mask the yellowish tint when viewed under a jewelry store's fluorescent bulbs. You might be surprised by the diamond's true yellowish appearance when you look at it at home under different lighting. Your best bet is to examine the diamond in as many different light sources as possible. 

The reverse is true for diamonds that fluoresce yellow. They can appear more white under incandescent lights, but acquire a yellowish tint in ultraviolet light.

Fluorescence in Jewelry with Multiple Diamonds

Most fluorescence is subtle. You probably will not see it as a true color change. You may notice a slight shift in tone. However, the difference could make a diamond ring or other jewelry with multiple stones seem out of balance if some of the stones fluoresce and others do not, or if they fluoresce different colors. Even though all the diamonds may be the same color grade, if they have a different fluorescence, the look may be uneven and appear unmatched.  This is why many jewelers will pick diamonds for a single piece of jewelry under a special ultraviolet light (similar to a black light).

Pricing for Diamonds that Fluoresce

A strong yellow fluorescence brings diamond prices down, sometimes quite a bit. This is because yellowish tinted diamonds are less desirable than whiter stones.

A blue fluorescence can help increase the prices of diamonds with yellowish tones because it makes a lower color diamond appear whiter than it is.

It's important for you to be happy with the diamonds you buy. Ask your jeweler to show you examples of fluorescence and try to look at diamonds in many types of light before you make a decision, especially if you are considering diamonds with no grading documentation.

Edited by: Lauren Thomann