Diamond Fluorescence

When you hear the term “diamond fluorescence,” perhaps you think of one of those neon-colored markers you use to highlight important notes at school or work. But fluorescence in a diamond? This probably sits outside your area of expertise. We’d like to help you understand this important aspect of diamond quality so that you’ll know what to look out for when it comes time to purchase an engagement ring.


What Is Fluorescence in A Diamond?

So, just what is diamond fluorescence? Fluorescence is the glow you see coming from a diamond when it’s exposed to ultraviolet (UV) light, such as a “blacklight” in a nightclub or the lamp used to dry your nails at the salon. Once away from a UV light source, the diamond will stop fluorescing. Approximately 25-35% percent of diamonds exhibit some degree of fluorescence, according to the Gemological Institute of America (GIA), the internationally recognized authority on gemological research, standards, and education.

What Does Fluorescence in A Diamond Mean?

Though it’s not one of the diamond-grading factors like the “4Cs” (color, cut, clarity, and carat weight), diamond fluorescence is considered to be an identifying characteristic of a stone and affects its value.

Grading reports from the GIA will note fluorescence in diamonds. For the intensity of diamond fluorescence, the GIA rates diamonds from None, Faint, Medium, Strong to Very Strong. If the diamond’s fluorescence is Medium, Strong, or Very Strong, the color of its fluorescence will also be noted in the grading report. Diamonds usually emit blue-colored fluorescent light, though it can vary from green to yellow to red and even white.

While exposure to UV light brings out diamond fluorescence, sunlight will not produce the same effect. Under typical lighting conditions, a diamond’s fluorescence is undetectable to the naked eye. However, diamonds rated with Strong or Very Strong fluorescence may exhibit a milky or oily appearance, even in normal daylight, which significantly detracts from their beauty.


Does Fluorescence Matter In A Diamond?

When it comes to diamond fluorescence, good or bad isn’t really the correct distinction. Some people like fluorescence, and some people do not. However, fluorescence will always meaningfully impact a diamond’s value.

A diamond with Very Strong or Strong fluorescence will have significantly less value, and even Medium fluorescence will negatively impact a diamond’s overall value.

When comparing options, inexperienced buyers often misunderstand the price differences between diamonds with None or Faint fluorescence versus those with Medium, Strong, or Very Strong fluorescence. It’s a common mistake to assume that a lower-priced diamond with stronger fluorescence is a better value. In fact, the exact opposite is often true!

For this reason, we recommend limiting your search to a diamond with Faint flourescence to no flourescence at all. We feel so strongly about this that we do not even sell stones listed as Medium, Strong, or Very Strong on the diamond fluorescence scale. Kwiat’s certified diamonds always have either None or Faint fluorescence, so that your ring will keep its beauty—and its value—through the years.