How Diamond Fluorescence Affects Beauty & Value (Advice)

What do we mean when we talk about diamond fluorescence? Have you ever heard of it before? Are we talking about diamonds that glow in the dark?

Aside from the 4Cs of diamond grading, there are other elements involved in the physical or chemical make-up of a diamond.

While fluorescence is often associated with raves, clubbing, and overly whitened teeth…where diamonds are concerned, it can be considered a classier affair.😎

Illustration of Diamond Fluorescence Effect

In this article, we will dive into the ins and outs of diamond fluorescence and the effects of fluorescence on a diamond's beauty and value that many do not know.

Let’s get started!

Basics: What is diamond fluorescence?

Fluorescence is what is referred to when discussing a diamond’s capability to exude a soft colored glow when subjected to ultraviolet light.

Think back to the disco or clubbing days where you would hit the dancefloor with your glow sticks and fluorescent disco wear only to be lit up like a highlighter as soon as you entered the blacklight area.

Those were the good days.

Well, our diamonds can light up just like our neon blacklight posters under UV light.

It is important to understand that a common myth is that “all diamonds are fluorescent”.

According to GIA research, this is simply not the case. Their research has shown that roughly 25% to 35% of diamonds exhibited any degree of fluorescence when examined under ultraviolet lighting conditions.💫

So whilst they aren’t super-duper rare, most diamonds do not exhibit a fluorescent glow.

The most popular color to be seen from a fluorescent diamond is blue. Whilst diamonds can fluoresce in many other colors such as yellow, green, and red, blue fluorescence accounts for the vast majority of fluorescent diamonds found.

What causes diamond fluorescence?

Let’s talk science (just for a short tick!).

When a diamond is found with trace amounts of elements including boron, nitrogen, or aluminum, the presence of these in a diamond’s atomic structure can absorb energy from UV sources.

Once this energy is absorbed, these tiny trace elements don’t know what to do with themselves!

They need to find a way to release that energy and they do that by emitting it in the form of photons.

All you need to know is that this is what we then observe as a fluorescent glow.

Understanding the diamond fluorescence scale

Before we dive into the juicy heart of this article, now is probably a good time to mention that fluorescence is not a determining factor of a diamond’s quality.📝

Whilst it may have an effect on the overall look of a stone, and it may enhance certain color graded stones whilst negatively impact others (more on that to come), fluorescence is not a characteristic considered in the GIA diamond quality grading system (4Cs).

Diamond fluorescence vs. 4Cs

The GIA considers diamond fluorescence to be an identifying characteristic along with polish and symmetry.  This means that there are further attributes that can be distinguished within a stone that may be of interest to the buyer, however, it is the 4Cs that primarily determine the quality and value of a stone.

Whilst the 4Cs look at the cut, color, carat, and clarity of a diamond—a diamond’s fluorescence is determined by its intensity.

GIA fluorescence scale

The GIA formulated a relatively simple grading system for measuring the intensity of a diamond’s fluorescence as seen in the image below.

GIA Diamond Fluorescence Grading Scale (Illustration)

The five categories in this system include:

  1. None
  2. Faint
  3. Medium
  4. Strong
  5. Very Strong

As you can see, the greater the intensity of a diamond’s fluorescence, the greater it glows. It is this strength or intense reaction after being exposed to UV light that determines the grading of a fluorescent diamond.

In the image above, the same stones are positioned underneath the UV image to show their appearance under "normal light". And, it’s pretty hard to tell the difference? Yet, look at the difference this fluorescence actually makes.

According to the GIA, while up to 35% of diamonds exhibit signs of fluorescence, only 10% of them show a fluorescence intensity that actually affects the diamond’s appearance.

According to a GIA study, “For the average observer, meant to represent the jewelry-buying public, no systematic effects of fluorescence were detected. Even the experienced observers did not consistently agree on the effects of fluorescence from one stone to the next”

This came from comparing four different diamonds with varying fluorescent intensities with the naked eye!

AGS fluorescence scale

The American Gem Society uses a similar tactic but with a slight twist to their grading systems.

The AGS takes a top-down approach to grade their fluorescent diamonds. Meaning, they grade each diamond in the "face-up" position. The reason they do this is that this is how the diamond will be set into a piece of jewelry.

The wearer of these stones will view them in this "face-up" position and so they believe this is the best way to get a true idea of how the stones will appear when set in a special piece of jewelry.

It makes sense, right?

Another way in which they differ is that they have altered the five categories of grading fluorescence intensity as used by the GIA (cheeky!).

Rather than using the two lowest categories; None and Faint, the ASG has combined the two and now labels them as "Negligible" as seen in the image below.

AGS Diamond Fluorescence Grading Scale
Image: AGS

Why I hear you ask?

Because in the face-up position, as used in the AGS grading process, these two categories are incredibly indistinguishable from one another and have very little effect on the appearance of the diamond.

Therefore, they’ve made life a little simpler and combined them into one—Negligible.

How to know whether a diamond has fluorescence and its intensity?

So, when you walk into a jewelry store are you going to be blinded by blue fluorescent light? Will you feel as though you are back on the dancefloor, will you be overwhelmed by flashes of neon everywhere you turn?😎


When can we see a diamond’s fluorescence?

We can only hope to see (most often) the blue glow of a fluorescent diamond when it is exposed to UV light or other sources of high-energy radiation such as X-rays and lasers.

So, you may notice a glow under the bright summer sunshine, at your weekly visit to the tanning bed, at a nightclub, or in other places where strong UV lights are used.🌄

However, once removed from under this light source you will instantly see the fluorescent glow diminish.

Whilst many people panic over the negative stigma associated with fluorescent diamonds, you will not live your day-to-day life with your diamond engagement ring glowing like a Star Wars lightsaber.

The times where a hint of fluorescent glow appear are likely to be far and few between…Unless you visit that tanning bed daily?

Diamond reports explaining fluorescence scale

If purchasing from a reputable jeweler then it is possible to receive a diamond report which will explain the quality assessment of the chosen diamond.

This will include the 4Cs, of course, along with other identifying factors as mentioned earlier, such as fluorescence.

An example of a GIA diamond report might look something like this:

GIA Report Fluorescence Info

Whereas an example of the AGS diamond report might look something like this:

AGS Report Fluorescence Info

Buying fluorescent diamonds from jewelers

To help us find what we desire, there are a handful of jewelers who will allow us to filter the fluorescence grading into our search for the perfect diamond.

An in-depth filtering and search system might include a tab that looks like this:

The Fluorescence Option on James Allen When Finding a Diamond

Allowing us to be more specific in our search and have greater control over what we are hoping to find.  Below is a list of four jewelers who do exactly that!

  1. Brian Gavin
  2. Blue Nile
  3. James Allen
  4. Whiteflash

However, the reason they are able to do this is that they offer loose diamonds. Their custom-made option means that we, the buyer, can handpick every element of the jewelry piece we wish to design…this includes the individual diamonds.

With larger, more prominent jewelry retailers such as Kay Jewelers or Zales, the selling of finished diamond jewelry may not provide such options.

It can hinder the amount of control we have to get the best value and even save money on our diamonds.

Top Tips
If buying online, do not hesitate to reach out to an expert who can help you confirm the fluorescence of a particular stone.

Ask them for a real-time inspection to clear any confusion you may have relating to the fluorescence.

If buying locally, ask a professional for guidance to find a stone with a fluorescence that is acceptable or beneficial to you.

How fluorescence affects a diamond’s beauty and value

Does fluorescence affect a diamond's beauty and value, I hear you scream?

It’s perhaps the most important question that we all want to be answered, after all, isn’t this why we buy diamonds in the first place?

There is an unfortunate negative stigma attached to fluorescent diamonds that would have buyers believe that it results in a lower quality, less desirable diamond. However, this isn’t necessarily the case.

As with most things in life, there are a number of factors involved when deciding what makes a diamond desirable or not.

The 4Cs make for a pretty definitive grading system and will always be the most important grading attributes when purchasing a high-quality diamond. Yet, these other characteristics, such as fluorescence, also play their part but not always in a way that you might expect.

Fluorescence does not affect the beauty and value individually

⚠️Fluorescence does not affect the beauty and value of the stone as a standalone attribute. And so, for those of you running for the hills trying to avoid those fluorescent diamonds…hold your horses!

Believe it or not, there are some circumstances where blue fluorescence is actually of benefit to the stone. It is not as cut and dry as you might think.

When buying a colorless or "white" diamond it is best to search for blue fluorescence (rather than fluorescence in other colors) or none at all. Blue and yellow are complementary colors which means that they neutralize one another.

You know where this is going, right?

So, we can use blue fluorescence to ENHANCE some diamonds that exhibit a yellow hue.

But please note that such “enhancement” may cause different degrees of milkiness or haziness in the appearance of the stones, according to their color grades and relevant qualities. More on that to come!

We’re now going to look at how fluorescence can affect the beauty of a diamond when coupled with different color gradings.

Important Information
Whilst the combination of color and fluorescence plays an important role in the overall beauty of a diamond, the cut quality will always play the biggest role in a diamond's brilliance and fire.

The cut is always considered the most important determining factor in a diamond's final overall appearance.

Whilst the color and fluorescence combinations mentioned below do have an effect on the appearance and quality, cut reigns supreme.

How it affects a colorless diamond (D-F)

Without a doubt, if you are lucky enough to be on the scout out for a colorless diamond in the D-F range then you might not want to hinder that with fluorescence.

If you cannot even afford a diamond in this color grading range without fluorescence, you can opt for a fluorescence intensity of Faint. Keep the blue glow to a minimum and bask in the purity of the brilliant white diamond.

However, some may WANT the blue glow. Yes, that’s right, it’s an incredibly subjective decision much like colored gemstones. If this is the case then choose Strong or Very Strong intensity.

Understand that it might take us a long time to find a diamond of this type without the appearance of milkiness or haziness. Brian Gavin’s Blue Collection is a great place to look for a diamond such as this as all diamonds are assured to exude optimal brilliance and sparkle!

How it affects a Near-Colorless diamond (G-H)

Now, here is where things become interesting…

In this category, your diamond is likely to have a slight hint of yellow hue. Perhaps not enough to be detected by the untrained naked eye yet enough for it to be placed in this lower category.

The glow of a blue fluorescent diamond counteracts this yellow hue and can actually give the appearance of a more pure, white stone.


So, in this case, a Medium or even Strong intensity level may provide maximum value. You can get the look of a premium diamond without the price tag.

But remember, as the fluorescence intensity increases so is the likelihood of a milky or hazy appearance. Additionally, a diamond with fluorescence will be less valuable especially in the resale market. Something to take into consideration!

How it affects lower color grade diamonds (I-J or lower color)

The same principle here applies as above.

To better counterbalance the yellow, warmer hues of the diamonds in this color category you might consider opting for a stone with a Medium, Strong, or even Very Strong intensity.

The hazy or milky appearance of a diamond with fluorescence may also occur in lower color grade diamonds. So, for full transparency, although this could make a great deal of difference to the "white look" of a diamond, it isn’t easy to make a diamond in this category look colorless. However, it could do a great deal in maximizing the whiteness and value!

Milkiness, haziness, and transparency

There are a few contradicting studies and opinions where milkiness and haziness are concerned. However, it would be rude not to touch upon these points.📰

Medium to Very Strong fluorescence can cause milkiness and haziness in a handful of stones. Because of this milkiness, the stone loses some of its transparency which is undesirable for most.

Yet, it is important to reiterate the point that this, as a side-effect to fluorescence in a stone, is not easy to distinguish by the jewelry-buying public under natural light.

Unlike fluorescence, symmetry, and polish which are qualities indicated on GIA certificates, milkiness and haziness are not. So, where possible, check with your designated jeweler to gain reassurance that this is not the case with your diamond before moving forward.

Unfortunately, studies from the GIA state that a hazy and milky finish caused by fluorescence is rare but have continued to admit that further studies do need to be conducted.

Whilst other industry experts appear adamant that this is in fact the case.

So, I think the most important thing to understand here is this; fluorescence may cause a foggy or milky tone in your diamond but it appears unlikely if we don't wear it under light sources that contain strong UV light.

Either way, the best thing you can do is check the stone for yourself with the help of an industry professional.

🎈Ultimately the desired look and finish is subjective and so this may not sway your decision as much as it might do for others.

Fun Fact
The strong blue fluorescence diamonds that possessed this undesired foggy appearance were labeled by the GIA as "overblues".

"Overblues" are incredibly rare and therefore not often seen in the marketplace.

What about the value of fluorescent stones?

Ultimately, the presence of fluorescence in a diamond should have very little effect on its value. The 4Cs dominate where diamond quality is concerned yet fluorescence intensity does make a difference to the overall cost of a diamond, particularly in certain color and fluorescence pairings.

  • As we have just seen, a colorless diamond will benefit from having very little fluorescence present. When it does, the value can decrease as it is deemed less preferable.
  • Yet, when we pair certain fluorescence intensities with diamonds of the lower color grade they can actually offset the presence of a yellow hue and add to its value.

Please look at the pricing chart below to get a comprehensive overview of how a diamond’s value will alter according to its color and fluorescence intensity.

Very StrongStrongMediumFaint
D-F-20 to 0%-18 to 0%-8 to 0%-6 to 0%
G-H-15 to 0%-12 to 0%-5 to 0%-3 to 0%
I-M-11 to 2%10 to 2%-2 to 2%-2 to 0%

*The price changes are for reference only, and would also depend on other quality factors such as diamond clarity, etc.

BONUS: Fancy colored diamond and fluorescence

Oh, you thought only colorless diamonds could glow?

Fancy-colored diamonds are certainly not left behind where fluorescence is concerned. Whereas it is more likely that colorless diamonds will be found with a blue or yellow fluorescent glow, fancy colored diamonds are more likely to be found in a variety of different shades such as blue, yellow pink, green, and orange.

In a similar style, the presence of fluorescence can enhance or hinder the stone’s overall beauty.

An example of how it may be of benefit may be the presence of Very Strong Green fluorescence in a Fancy Vivid Green Yellow diamond.

The very strong green fluorescence could easily add to the intensity of the Fancy Vivid Green Yellow diamond with its added green glow!

So, is diamond fluorescence good or bad?

This might not be what you want to hear, but there is no right or wrong answer!

Unlike the undoubtful certainly of the 4Cs grading system, the presence of fluorescence in your diamond stone does not necessarily mean it is a good or a bad thing.

Yes, fluorescence has received some negativity over its lifespan yet this is often because it is misunderstood. Rather than looking at whether fluorescence is "good" or "bad" let’s way up some pros and cons for easy comparison.⚖️


  • The presence of fluorescence in diamonds is relatively common with approximately 25%-35% of diamonds exhibiting some degree of fluorescence. Meaning, you may have seen more fluorescent diamonds than you even realize!
  • To the untrained eye, it is not easy to tell the difference between a diamond with no fluorescence to one with Very Strong fluorescence under natural light.
  • The dazzling beauty of a fluorescent stone under UV light can be truly breathtaking and is admired by many.
  • A diamond’s fluorescence has no influence on its durability. So this should not be of concern.
  • The presence of fluorescence can increase the value of a diamond with a lower color grade.


  • It is a common misbelief that a fluorescent diamond is of lower quality.
  • Medium, Strong, or Very Strong fluorescence can cause milkiness or haziness which affects the transparency and overall beauty of the stone.
  • The presence of fluorescence is not overly sought after in colorless diamonds (DEF) as it can detract from their natural purity.
  • Because fluorescence can often be viewed as a "defect" it may be difficult to sell your diamonds further along the line. If you are hoping to resell your diamonds in the future, a stone with no fluorescence may be preferable.

How to consider the fluorescence when buying a diamond? (Advice)

Here are some of our top tips for taking fluorescence into consideration when shopping for your next diamond…🛒

  1. Fluorescence is an identifying characteristic of a diamond, it is not a default. Use this information to find out how traces of fluorescence can actually be of benefit to you in the buying process.
  2. It all comes down to your own personal taste. If you love the unique quality of a diamond with a very strong intensity then do not let the nay-sayers stop you from buying what you love.
  3. Where possible, view the diamond up close and personal. Whilst there are many jewelers who offer services online to help you purchase the best possible diamond for your buck, nothing beats seeing the glistening stone in real life. You will have a far better understanding of the effects of fluorescence on the diamond if you are able to do this.
  4. Do not hesitate to ask the retailer to view the stone under various different lighting to see the full effect of the fluorescence under different lighting environments.
  5. If we fall in love with the fluorescence effect yet want the diamond to shine and sparkle without milkiness and haziness, it would take time to search for that perfect stone. Brian Gavin has rolled out the Blue collection to provide diamonds with these features at an affordable price.
  6. Always check the retailer returns policy when buying diamonds with fluorescence. Blue Nile offers a 30-day return, James Allen promises hassle-free returns within 30 days, and Brian Gavin Blue offers a 15-day inspection period. These guarantees can allow you to feel more relaxed and reassured when purchasing a diamond with fluorescence.😊

Should you buy a fluorescent diamond?

As you have hopefully come to discover, there are a variety of factors involved in determining whether a diamond with fluorescence is right for you.

But, in this case, it is highly subjective and mostly down to personal preference.

💡The important thing to note is that the presence of fluorescence is not necessarily negative as many people often believe. It can be a beautiful trademark of your diamond, it can stun and dazzle under the neon light, and it can make a diamond of lower color grade appear purer.

Whatever you decide, understand that your own personal taste is what matters most.

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