Fluorescence in Diamonds 101


Fluorescence in diamond is the bluish light that we see from diamonds when it is exposed to UV light from the sun or under a fluorescent lamp. It happens when the diamond was crystalizing, and the element boron was present. The amount of boron present will cause the diamond to fluoresce either faintly, medium, strong, or very strong. These will be the four intensities in which we can describe the level of fluorescence present in a diamond.

Think of it as the effect we get when we go to a black light party or when our teeth are exposed to UV lighting. They glow and that’s what fluorescence in diamond looks like under the same form of lighting.

Fluorescence usually appears blue but it can appear in different colors as well, such as yellow, green, red, and sometimes even pink.

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About 25% to 35% of diamonds have some fluorescence. Depending on a diamond’s grade, this can be a positive thing or a negative thing, although oftentimes fluorescence in a diamond has a neutral effect.

Fluorescence: Good or Bad?

Fluorescence in diamonds has very good selling points. Given the notion it has with the consumers, it can drive the price of a good quality diamond and afford you a great discount. You can use this fear factor or disinformation to your advantage in getting a discount, but nowadays this might not be as effective as more consumers are made aware that fluorescence does not lessen a diamond’s quality but only affects its overall appearance.

If you’re after higher color grade diamonds, then fluorescence can affect the quality of the stone you’re purchasing but for lower color grade diamonds, this can actually make your diamond appear whiter. Since fluorescence is a function of color in diamond it impacts the color of the diamond.

Here’s a quick reference guide by GIA on a diamond’s color scale.

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So, if you’re on a budget but want a beautiful sparkly diamond, you can opt to get a lower color grade diamond with medium to strong fluorescence. Say buying a K to M diamond with medium to strong fluorescence will make it look like an I-graded diamond in daylight. Sparkly and beautiful but for a cheaper price! That’s a good steal.

Fluorescence cannot be easily determined by untrained eyes. Even professional gemologists have difficulties assessing if there is fluorescence in a diamond without proper lighting equipment.

One notable negative thing about diamond fluorescence based on a study conducted by GIA, shows less than 1% of diamonds in the market display haziness or a milky appearance compared to a diamond with no fluorescence. They usually have strong to very strong fluorescence intensity grades. 

The milky appearance associated with fluorescence is also present in other diamonds with no fluorescence and this is because of the graining or the irregularity in crystal growth that makes a diamond appear hazy in certain lighting.

Fluorescence and its Effect on Price

A diamond’s price is determined by its 4Cs: cut, color, clarity, and carat weight. Adding fluorescence to this equation will make looking for a specific diamond a little bit more challenging. 

For example, buying an F color diamond with high clarity like a VS1 or a VS2 with strong fluorescence will cost 3% to 5% less than that of a diamond of the same quality with no fluorescence and a K color diamond with strong fluorescence will cost 2% more than that of a diamond with no fluorescence. It is made clear that a diamond with a higher color grade with fluorescence affects the price and lowers it while a lower color grade diamond with fluorescence will cost higher as it affects the appearance of the diamond positively.

Here’s a quick chart by lumera diamonds on the relationship between price and fluorescence.

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Myths About Fluorescent Diamonds

  1. All diamonds are fluorescent-based on a study made by GIA, only 25% to 35% of the diamonds they have tested fluoresce, while AGS uses the term negligible for faint fluorescence present in diamonds because a stronger UV light source can cause those to show some fluorescence.
  2. You can see fluorescence in diamonds easily – diamonds fluoresce under long wave UV light such as sunlight or UV lamps. You can notice a diamond fluoresce under direct sunlight or in a blacklight party in a club but it is difficult to be certain without UV lighting or in a controlled laboratory environment.
  3. Diamond fluorescence is always blue – some diamonds fluoresce in different colors such as yellow, yellow-orange, orange, green, white, and red. Blue is the most common diamond fluoresce color,
  4. Diamond fluorescence affects brilliance – fluorescence in diamond has little to no effect on a diamond’s brilliance and sparkle. This is determined by the diamond’s cut that affects the measurement of its facets and craftsmanship affects the quality of the cut and how well it reflects light and thus, sparkles.


In conclusion, fluorescence in diamonds is neither good nor bad. It all boils down to personal preference. It all falls down to whether knowing your diamond fluoresce bothers you or not. It is best to inspect the diamond before making a purchase in different types of lighting conditions. Diamonds sparkle differently based on the light it is reflecting back. If a diamond fluorescence brings you happiness and it makes your heart fill with joy, then that’s the way to go. The beauty of diamonds is subjective to the wearer. Pick out the one that you deem most brilliant and sparks the most joy out of you.

It’s kind of cool to see your diamond jewelry fluorescing while you’re on the dance floor busting your moves.

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