Is Fluorescence in Diamonds Good or Bad?

What's the deal with diamond fluorescence?

We really don’t mean to sound non-committal on this one, but for the most part fluorescence in a diamond is neither good nor bad. The truth is that most people won’t even perceive it. Some people can do it, but for the most part fluorescence in a diamond will impact your life about as much as dressing on someone else’s salad.

Bottom line, anything under ‘medium’ will make zero difference to the quality of the diamond. Even if you find a stone that has ‘very strong’ fluorescence, this doesn’t mean that the diamond will be anything other than fabulous. It just means that you need to be aware of how that fluorescence might affect the look of the stone (but probably won’t).

So when is fluorescence a problem?

Fluorescence in a diamond can impact the color in very rare cases. The good news is that this mostly involves making the stone appear whiter. This happens in lower color grades, where the blue of the fluorescence actually negates the yellow hue of the color in the stone, making it appear whiter.

A cloudy day

In terms of the transparency of the diamond however, things can be trickier. Sometimes fluorescence in a diamond can cause the stone to look ever-so-slightly milky or hazy. Some people don’t notice this at all, some notice it immediately, while others will only spot it in certain kinds of lighting. The golden rule is to examine the stone thoroughly before you buy.

Need more info on fluorescence? Of course, you do.

Diamond Fluorescence FAQs

What exactly is fluorescence in a diamond?

Fluorescence is the glow a diamond emits when exposed to ultraviolet (UV) light. Most buyers won’t see this effect in everyday wear—it’s often only noticeable under UV or black light.

Does fluorescence automatically make a diamond look worse?

Not at all. The article explains that for the most part, fluorescence is neither good nor bad—it has minimal to no visible impact in everyday lighting.

Can fluorescence ever be a benefit when buying a diamond?

Yes. Especially for diamonds with slightly lower color grades, a bit of blue fluorescence can help mask yellowish undertones, making the diamond appear whiter in certain lighting.

When should I be cautious about fluorescence?

Good question. Strong or very strong fluorescence in high-color-grade diamonds (for example D–F) may occasionally create a slightly hazy or milky look in some light conditions. That’s why it’s smart to view the diamond in person or through good-quality video before buying.

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Dr. Rian Mulcahy

Rian is officially a Diamond PhD - just ping us if you’d like to read her fascinating 200-page thesis, titled Facets of Value: An Investigation into the Formation of Worth in the Diamond Market. She has consulted various firms all along the pipeline, from the rough diamond market to the recycled diamond industry. She holds an MA in Globalisation and Development from University College Cork and a PhD in the Sociology of Diamond Valuation from the London School of Economics.