What Does Fluorescence In a Diamond Mean

When shopping for a piece of diamond jewelry, a term you might hear frequently is fluorescence. Fluorescence can affect the price of the piece you want to buy, so it helps to familiarize yourself with the term.

This article will explain what fluorescence in a diamond means. In the end, you will be in a position to make smart decisions when shopping for your jewelry.

What Is Fluorescence In A Diamond?

What Is Fluorescence In A Diamond
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Fluorescence is light that a diamond emits when exposed to UV rays or daylight. To the naked eye, fluorescence is invisible, and unless you are an experienced jeweler, you might not tell when and whether a piece of diamond emits this invisible light.

You would need very strong UV rays or intense sunlight to detect fluorescence. Even gemologists and jewelers use advanced equipment to determine the amount of fluorescence in a piece of diamond.

According to the Gemological Institute of America (GIA), fluorescence light can be faint, medium, strong, or very strong. Some diamonds may exhibit no fluorescence light at all. This invisible glow is usually blue, but some diamonds may emit yellow fluorescence.

Some diamonds may fluoresce green, white, red, or orange in rare cases, but this typically occurs in very few diamond varieties. Compared to blue, these other colors are less desirable in diamonds.

If you would like to learn more about the technicalities of how and why diamonds fluoresce, you can take a look at this helpful video.

Is Fluorescence Good Or Bad?

Fluorescence gets a bad rap, but the truth is, this bluish glow on a diamond is neither entirely bad nor good. The light can affect pieces of diamond in different ways depending on factors such as the diamond’s initial color.

Fluorescence can make a piece of diamond look hazy, or it can improve the diamond’s color. This depends on the diamond’s color grade based on GIA’s grading system. First, before discussing whether fluorescence is good or bad, let us look at GIA’s diamond color grade chart. The stones are categorized from D to Z when grading diamonds by color and brilliance.

  • D-F: Diamonds in this category are colorless and are considered the most chemically pure.
  • G-J: These diamonds are almost colorless; a trained grader might notice that the diamond is not entirely colorless.
  • K-M: The diamonds here are categorized as faint with a slight hint of color. Even then, it is difficult for the untrained eye to notice the slight color.
  • N-R: This category of diamonds is referred to as very light. An untrained eye would be able to see the color in larger stones.
  • S-Z: These diamonds have a noticeable color; the stone may appear brownish or yellowish in larger stones. These should, however, not be confused with fancy colored diamonds.

However, keep in mind that the color variation among the various diamonds is subtle; only a trained jeweler or gemologist might notice these variations.

Diamonds in the D-F and G-J range do not benefit from fluorescence. Fluorescence can make these colorless diamonds appear hazy, which is an undesirable quality in diamonds. As such, colorless diamonds with fluorescence will often be priced lower than colorless diamonds that do not emit fluorescence. The clearer the diamond, the more beautiful it appears, and the pricier it is.

In diamonds with some color in them, especially those in the N-R and S-Z category in the GIA color chart, the presence of fluorescence can be beneficial. Medium, strong blue, and very strong blue fluorescence can make these ‘colored’ diamonds appear whiter and less hazy, which is always a welcome improvement.

Advantages Of Fluorescence In Diamond

As I have mentioned, fluorescence is not necessarily a bad quality. The presence of fluorescence can make a piece of diamond more affordable without sacrificing quality.

Generally, diamonds with more clarity, i.e., those belonging to the D-F category, may attract a bigger discount if they emit medium to very strong fluorescence. Check out this video for a detailed explanation on how fluorescence might save you money.

Fluorescence does not take away from the inherent quality of these high-grade stones. Still, because the glow can cause some of these stones to appear hazy, fluorescence is not always desirable and may slightly lower the diamond’s value. For example, a D-F-colored diamond with faint fluorescence might attract a discount of 1% off the retail price. In comparison, the same stone with a strong fluorescence can be discounted by 7 to 15%.

On the other hand, diamonds with some color, for example, those belonging to the N-R and S-Z color grade, might benefit from fluorescence; the more blue fluorescence these stones emit, the brighter they appear. As such, N-R and S-Z stones exhibiting fluorescence might be prized higher than stones in the same color grade that do not have fluorescence.

For example, an S-colored diamond with faint or no fluorescence might not attract any discount, but the same stone with medium to very strong fluorescence might be prized 2% more.

All in all, fluorescence does not affect the innate quality of a piece of diamond. In some instances, the light reflection might be beneficial when it makes a tinted or near-colorless diamond appear brighter. Diamonds with a strong blue fluorescence are not necessarily bad. Tinted diamonds will look very attractive and almost colorless under strong  UV light.

Is A Fluorescent Diamond Worth Buying?

Is A Fluorescent Diamond Worth Buying
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As we have seen, fluorescent is simply the light that a piece of diamond emits under strong daylight or UV light. This light or glow is not necessarily a bad quality. Depending on the diamond’s color grade, fluorescence might benefit some diamonds by improving the color.

Some diamonds that exhibit fluorescence can appear much brighter than those with no fluorescence; this is particularly true for tinted diamonds such as K to Z colored stones, which become brighter and lose their milky haziness when the diamonds fluoresce.

On the other hand, diamonds in the D-H color range may not necessarily benefit from strong blue fluorescent. Too much fluorescence can make these diamonds appear hazy and therefore less desirable if you are looking for a high-grade diamond with a brilliant shine.

So, whether or not you should buy a fluorescent diamond will depend on the type of stone you are looking for in the first place. Diamonds in the D-H color range are considered the purest and have a higher price tag than tinted diamonds.

We all know that diamond is not cheap. But, you might be able to save some money on your jewelry by buying a fluorescent diamond. Not all diamonds fluorescence, but those that do are often sold at a discount, and you might be able to secure a sweet deal on your diamonds.

If you are considering a colorless or almost colorless diamond, one with medium blue fluorescence might be a good choice. The fluorescence isn’t too much that it takes away from the diamond’s natural brilliance, and you might be able to purchase it at a discount of as much as 5% of the price of a colorless diamond with no fluorescence.

Diamonds with a bit of color often appear hazy and milky and are priced a little lower. But fluorescence can increase the brightness of these diamonds, causing them to attract a slight price increase. If you are on a tight budget, opt for a colored diamond with strong blue fluorescence, as this will cause the otherwise hazy diamond to appear brighter under strong UV light.


Overall, the stone’s appearance is more important than the fluorescence. The truth is, most regular people cannot tell whether a diamond is fluorescent. So, whether you are buying a diamond bracelet, necklace, or ring, you should be concerned with whether you like how the diamond looks. If it feels and looks good, then that is the diamond that is worth buying.

As we’ve seen, fluorescence has its advantages and can sometimes elevate the appearance of the diamond while attracting a small price deduction. However, color, clarity, cut, and carat is more important than fluorescence when deciding the best stone for you. It is still helpful to talk to your jeweler about all the qualities of a stone, including the fluorescence, before making your final decision.

When shopping, ask to see the diamonds under normal lighting and UV, and if possible, in daylight. This will help you catch a glimpse of the level of fluorescence in the stones—most reputable jewelers will not have a problem with this.

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