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Don’t Let Diamond Fluorescence Ruin Your Engagement Ring

If you’re shopping for a natural diamond you’ve most likely learned that 25 – 25% of natural diamonds fluoresce i.e glow blue under UV light and when you go outside. But what does the mean, really?

If you’re searching for this you already know that these strange little lumps of polished carbon emit a thing called fluorescence. You probably also know that the presence of fluorescence is the subject of debate online. But what is diamond fluorescence? Is it good or bad? Should you buy a diamond because of or in spite of it? Is a lack of information about fluorescence in diamonds the reason for all those glowing blue diamonds on Reddit? What percent of diamonds are afflicted with this strange and superhuman condition that’s more at home in a Marvel movie than an engagement ring? What does fluorescence in a diamond mean? Let’s dig in.

Each diamond has its own characteristics, so even stones with the same fluorescence grading will sparkle differently.

What is Diamond Fluorescence?

Fluorescence is a glow some objects and creatures emit under visible light. While it may sound unusual to us, there are many creatures in nature that emit fluorescence. From a flying squirrel that emits a pinkish glow under ultraviolet light to the ever likable puffin, whose beak glows blue under UV light to the chameleon whose skin is so thin that their bones glow in the dark. Similar to these cuddly creatures, diamonds generally emit a bluish light when they fluoresce, although some can emit yellow or orange light as well. No light = no fluorescence. While we’re not sure why some diamonds fluoresce and not others, we’re confident that the ability to glow can’t always be a bad thing.

Do All Diamonds Fluoresce?

A surprisingly large percentage of diamonds — 25% to 35% fluoresce to some degree. The GIA and other labs like the IGI and GCAL assess a diamonds fluoresce by how intense it is, ranging from none to faint, medium, strong, and very strong. Similar to color, fluoresce is graded against a set of master stones in the lab.

Can Fluorescence Make My Diamond Look Whiter?

For those of you who took color theory, this one’s a no brainer. For everyone else — pay attention. Diamonds come in shades of white and yellow. When blue is added to the yellow they cancel each other out. The more blue you add to yellow, the whiter it becomes. Therefore, a fluorescent diamond in the I-M range is going to appear whiter under UV light. Guess what contains UV light? Daylight. Magic or science? Who cares. Bottom line, you’re getting a whiter diamond for your money.

Unfortunately, the same applies the opposite way around. Fluorescent diamonds in the colorless and near-colorless range (D-H) will look bluish under UV light. They also can appear hazy or oily in appearance.

So, if you’re thinking about buying a fluorescent diamond, remember that fluorescence and color counteract each other. Fluorescence can make a yellow diamond appear white, or a white diamond appear blue.

Custom Frank Darling radiant cut engagement ring in platinum
Some slight fluorescence might give your diamond a more interesting fire!
You want to make sure you love your stone (it’s a huge purchase) so try to see it in person before you buy!

Will Fluorescence Ruin Your Engagement Ring?

Most likely not, but it’s the sort of thing you may want to discuss with your partner, especially if you’re shopping in “strong” or “very strong” grades. Also, similar to SI1 and SI2 diamonds, it’s a good idea to take a look at the stone in person, or have someone do it for you to make sure it’s not milky.

If you can’t do that, you may want to consider requesting additional images or videos under different lighting conditions to thoroughly assess the stone. If you want a stone that glows blue because it’s a great party trick we support that. You do you.

Are Fluorescent Diamonds Cheaper?

Yes and no. Fluorescent diamonds do trade at slightly different prices than non-fluorescent diamonds, but not the ones you want. I-M diamonds with strong fluorescence trade at a 2-3% price premium to non-fluorescent diamonds with similar color grades. Why? They face up whiter. Don’t you think they deserve the modest bump?

On the other hand, a D color diamond with very strong blue fluorescence trades at up to a 15% discount to similar diamonds sans the glow. You may be able to afford it, but do you want it? Probably not.

Diamond pricing is mathematical. Prices fluctuate because of supply and demand but also because of the make and characteristics of the diamond. While you may only get a modest discount because of the fluorescence, you will also get a whiter diamond than you may be able to purchase otherwise. Win-win? We tend to think so.

Diamond Fluorescence and Colorless diamonds

If you’re looking at diamonds in the D-F range, we recommend purchasing one without fluorescence. Even faint fluorescence is going to add a dash of blue to your otherwise white stone.

Colorless diamonds are some of the biggest fluorescence culprits due to their ultra-clean appearance.
G-H tends to be the sweet spot if you want to avoid a super blue look.

Diamond Fluorescence and Near Colorless Diamonds

For nearly colorless diamonds in the G-H range, we recommend faint fluorescence at most. Faint fluorescence can have the benefit of bumping your diamond up one color grade, making your “near-colorless” diamond appear “colorless.”

Diamond Fluorescence and Warmer Diamonds

If you’re shopping in the I-M range, you have a bit more wiggle room and will get a lot more bang for your buck. The lower the color grade, the stronger you can go in fluorescence as long as it’s blue.

Warmer colors with fluorescence will have an extreme rainbow effect.

Ready to Find Your Diamond?

Check out our diamond search where you can view 360-degree images of more than 10,000 diamonds and don’t forget to zoom out (because size can be deceiving), or book an appointment at our New York salon to view certified lab-grown and natural diamonds in person. 

Not finding what you’re looking for? Email us with what you’re looking for at We’ll curate a list of 5-7 exclusive stones that are just right for you.

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