Fluorescence can make a diamond look dull and lifeless. However, it does not have the same impact on all diamonds. In some cases, fluorescence might even play a positive role in a diamond’s brilliance.

Here are some scenarios when fluorescence might be beneficial:

Positive effects: Blue fluorescence can be a positive factor in diamonds with a yellow tint (H, I, J colors or lower grades). This is because blue is a complementary color to yellow, thus making a diamond appear whiter than its actual color.

Level of intensity: Fortunately, the intensity with which a diamond emits fluorescence is not the same. While stronger intensity often leads to a higher negative impact, diamonds with lower intensity ranges, such as faint or medium blue, often do not drastically harm a diamond’s brilliance.

It does not hurt all diamonds the same way: In some cases, fluorescence might make a diamond look overly dull or oily; in others, it might have no impact on a diamond’s visual appearance at all. However, most diamonds with fluorescence get discounted prices because of the perception problem, even if it does not affect their beauty.

Price: Because fluorescence is viewed as a negative factor universally without dealing with it on a case-by-case basis, it presents an opportunity for a buyer to grab an exceptional diamond at a discounted price because of the perception problem that fluorescence faces.

 

 

Summary of Key Points:

Over 95% of the time, the color of the fluorescence is blue, but diamonds can also fluoresce other colors. Yellow is the next common color a diamond will fluoresce.

Because of the invisible property, fluorescence will mostly have almost no impact on the aesthetics of the diamond. According to GIA, of the 25% to 35% of the diamonds submitted to them that had fluorescence, only 10% of those diamonds had a slight effect on the appearance of the diamond. A typical diamond wearer will not see that effect in faint and medium blue grades.

After evaluating hundreds of diamonds, we can confirm that exceptional diamonds are often avoided because of the fluorescence in them.

To understand the effects of fluorescence on a diamond, a buyer must understand how it relates to the color of a diamond. It is not a desirable factor in colorless white diamonds (D-F color range), though it can be helpful in H and lower color ranges.

The price of a diamond is not significantly affected if the diamond has faint fluorescence.

Recommendation:

• No fluorescence is best in D-F color diamonds. In G color diamonds, none to faint fluorescence is good. In H-Z color diamonds, medium to blue fluorescence can be a helpful factor because blue is a complementary color to yellow, making the diamond look whiter than its actual color.
• It is common for high-grade diamonds to have blue fluorescence, such as D, E, and F color diamonds. If possible, avoid fluorescence in colorless diamonds.
• Diamonds with very strong fluorescence are uncommon. Most diamonds with very strong fluorescence are blue.
• Avoid diamonds with fluorescence that makes the diamond look hazy, oily, or cloudy.
• If you buy a diamond with fluorescence, make sure you have a solid return policy in case the fluorescence negatively its beauty (making it look oily or hazy in front of the sun), which is the case in less than 10% of diamonds with fluorescence in them.
• To summarize, while fluorescence is generally considered a negative factor, it is often not treated as such in I to Z color diamonds, especially for faint or medium blue fluorescence.

Fluorescence Scale:

Carefully review the chart below as it contains our summarized insights on diamond fluorescence. Please also check the subsequent chart on discounts that you might get in each range and why color is a significant factor in determining such discounts.

The picture below shows how diamonds that emit different types of fluorescence look in regular settings. It is hard to tell the difference between diamonds with no fluorescence and ones that emit fluorescence while inspecting them with the naked eye. Observing this effect is a lot harder under indoor lighting and might be easier to detect under sunlight.

Price Discount Due to Fluorescence:

This diamond price discount breakdown by fluorescence type is our best estimation based on color. It might change depending on how big the stone is and the impact fluorescence on the diamond, especially if it is making it look dull or hazy.

Fluorescence	Things to Consider
None	Excellent
Faint (which is Faint Blue)	D-E Color – Good, 3-4% discount. F-G Color – Very Good, 2-3% discount. H and Above – Excellent, 0-2% discount.
Medium Blue	D-E Color – Fair, 6-8% discount. F-G Color – Good, 2-5% discount. H and Above – Very Good, 0-2% discount.
Strong Blue	D-E Color – Poor to Fair, 15-20% discount. F-G Color – Fair to Good, 12-15% discount. H and Above – Good to Very Good, 7-10% discount.
Very Strong Blue	D-E Color – Poor to Fair, 15-25% discount. F-G Color – Fair to Good, 10-20% discount. H and Above –  Fair to Very Good, 8-14% discount.

 

The above criteria might differ from diamond to diamond and the degree to which the presence of fluorescence in a diamond affects its brilliance. Generally, you will get a higher discount on D-E color diamonds that have fluorescence in them. In F/G colors, the discount might be lower in the faint range, but it might be higher in the medium-to-strong blue range. In H, I, and J+ color diamonds, you might not get significant discounts because fluorescence can positively influence the brilliance of a diamond in this color range. As mentioned earlier, blue is a complementary color to yellow and might make such diamonds look whiter than their actual color grade.

As confirmed in the Gemological Institute of America’s (GIA’s) study, we also believe that, in most cases, consumers cannot detect fluorescence in a diamond. A great majority of diamonds with fluorescence can have as much brilliance as those with no fluorescence. The milky, hazy, and oily appearance of a diamond can also be found in stones with no fluorescence.

The most important factor in a diamond is its appearance, and if you are happy with how it looks, do not worry about the fluorescence in it. In addition, enjoy the 4-15% discount that you might get when you buy a diamond with fluorescence in it. In our opinion, the discount should be up to 2% for faint fluorescence, up to 5% for medium blue fluorescence, up to 12% for strong blue fluorescence, and up to 18% for very strong blue fluorescence.

Summary of GIA’s Study:

Of the diamonds submitted to GIA over the past decade, around 25% to 35% exhibited some fluorescence level. In under 10% of these diamonds, fluorescence affected the appearance of the diamond. However, this effect is not negative and could sometimes be complementary to the brilliance of the diamond. The visible color is blue in over 95% of the diamonds that exhibit fluorescence, and since blue is a complementary color to yellow, tinted diamonds look more colorless.

None or No Fluorescence: After reviewing a random sample of 26,010 diamonds, GIA found that only 9,175 or 35% exhibited some level of fluorescence. In GIA’s words: “None” means that any fluorescence shown is weaker than the reference stone’s. “None/faint” is the GIA’s word for “none.”

Faint Fluorescence: After reviewing a random sample of 26,010 diamonds, GIA found that only 9,175 or 35% exhibited some level of fluorescence. Of the 9,175 diamonds, 38% or 3,465 reported faint fluorescence. Please note that the GIA considers faint fluorescence the lower end of blue fluorescence, e.g. faint blue fluorescence, medium blue fluorescence, strong blue fluorescence, and very strong blue fluorescence.

Medium to Very Strong Blue Fluorescence: After reviewing a random sample of 26,010 diamonds, GIA found that only 9,175 or 35% exhibited some level of fluorescence. Of the 9,175 diamonds, 62% or 5,710 had blue fluorescence ranging from medium to very strong blue fluorescence. While 97% of these fluoresced blue in varying intensities, 3% or 162 stones, fluoresced other colors such as yellow, white, and orange.

Of the 11,901 diamonds in the D-to-F range, a similar proportion fluoresced (4,250 diamonds, 36%).

Key Findings of the GIA Study:

1. For average buyers (consumers), no systematic effect of fluorescence was observed.
2. Most observers did not find any connection between fluorescence and diamond clarity.
3. Even experienced observers or graders did not agree on the effect of fluorescence on the stones they were given to evaluate.
4. Diamonds with strongly blue-colored fluorescence were perceived to have a higher grade than the actual color grade of the diamond.

Important Facts About Diamond Fluorescence:

Not all diamonds fluoresce. When the GIA analyzed about 26,000 diamonds, only 25-35% of them exhibited some level of fluorescence.

Fluorescence cannot be easily seen with the naked eye. You might see fluorescence under dazzling sunlight or in places with strong UV rays, such as a tanning bed. Once the source of UV rays is removed, you cannot see the fluorescence.

Fluorescence cannot be easily identified and detected. It is hard for trained gemologists to detect fluorescence in a diamond. Most gemologists often use advanced tools to determine the level of fluorescence in a diamond.

Fluorescence’s biggest connection is with diamond color. While technically there is no impact on the color grade, because blue is a complementary color to yellow, when you look at the same color diamond with fluorescence, it can make the diamond look whiter than its actual color grade.

Fluorescence is not a grading factor like the 4Cs. While GIA considers fluorescence an identifying characteristic in a diamond, we believe it is also an important price and quality factor. It can be helpful in certain diamonds, but is a negative factor in colorless ones.

Fluorescence is not just blue. While blue is the dominant feature of fluorescence, there are also yellow, orange, red, white, and green fluorescence colors. The other colors are usually less desirable and are least preferred compared to blue.

Strong blue fluorescence can be bad. Depending on the color grade, it can be a negative factor in colorless diamonds. Consider it on case by case basis, and inspect the diamond in person. You might get lucky and get an extra discount on a great diamond with strong blue fluorescence that has no negative impact on the diamond.

Fluorescence does not make a diamond less durable. It has no impact on the durability of a diamond, as the structural integrity of the diamond remains the same.

Fluorescence could work in your advantage, here is why:

1. You might get a 4% to 10% discount on your diamond purchase without compromising on the overall quality of the diamond. We believe that the discount should be up to 2% for faint fluorescence, up to 5% for medium blue fluorescence, up to 12% for strong blue fluorescence, and up to 18% for very strong blue fluorescence.
2. Medium blue fluorescence might enhance the color of your diamond if it is within the H-L range or lower.
3. Faint fluorescence will also help you save money on your diamond without losing its overall brilliance.
4. When buying a diamond with fluorescence, make sure you have the option of returning it just to be on the safe side.

Range of Diamond Fluorescence in GIA grading reports:

None or no fluorescence, medium blue fluorescence, strong blue fluorescence, very strong blue fluorescence, faint fluorescence, yellow fluorescence, and green fluorescence. Blue is the most common form of fluorescence in diamonds.

FAQs on Diamond Fluorescence:

If I had the option to pick between no fluorescence or faint/medium blue fluorescence, what would be the best choice for me?

No fluorescence is preferred. In H, I, and lower color diamonds, blue fluorescence is a helpful factor. If you can, avoid it in D-G color diamonds. Faint is also great for G color.

Why is fluorescence perceived negatively?

Given that it is not as easy to understand as carat weight or color for example, first-time buyers prefer to be on the safe side and assume the worst.

What about fluorescence in D-F color diamonds, and why should it be avoided in such a range?

In most cases, fluorescence in D to F color diamonds might not have a significant negative impact on the diamond’s beauty. However, it can make the diamond look bluish, which is why most people prefer to avoid it in this color range. On the other hand, some buyers prefer the bluish hue of white diamonds.

Is strong blue fluorescence really bad?

You might get lucky with strong blue fluorescence. Buyers assume it is a super negative factor and avoid it altogether. However, it is not as bad of a factor in I and lower color diamonds. It can help them look much whiter than their actual color, as blue is a complementary color to yellow, making diamonds look whiter than their actual color. In D- G color diamonds, it can be a negative factor. Therefore, make sure you either see the diamond in person or have a very strong return policy if you buy a D-G color diamond with strong or very strong blue fluorescence to determine how the fluorescence affects the stone’s brilliance in person.

Credit: Sharif Khan on 22nd Feb 2022