Diamond Fluorescence: The Complete Guide

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Each diamond has a different fluorescent level that may affect its total appearance. Depending on its level, the diamond can glow and show a bluish color, lose its brilliance and look milky. However, not all diamonds with fluorescence are affected by it, yet they are sold at a 10%-15% discounted price. Coming across such a diamond can be a fantastic deal, such as this beautiful 1.01 carat H VS1 diamond.

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Table of Contents

Although it may seem like a complex factor, diamond fluorescence can be simplified to make your buying experience more manageable. This article will discuss all the questions relating to this grade, break common misconceptions, and give you a set of rules to follow. After reading this, you’ll be able to make an informed buying decision.

Ready? Let’s dive in.

What is diamond fluorescence?

Fluorescence is the brightness you see when an object releases visible light. Some diamonds glow under exposure to ultraviolet light rays from fluorescent lamps or the sun. When this happens, the diamond starts to glow and show a bluish color. Moreover, in rare cases, they glow in yellow and orange. Each diamond has a different fluorescence level. Depending on the level, it may affect the total appearance of the diamond:

  1. A yellowish diamond can look whiter
  2. A colorless diamond can look yellower
  3. Some diamonds can turn completely blue
  4. It may cause a milky, cloudy and hazy appearance, resulting in no brilliance and sparkles.

Some customers buy a diamond, receive it, and don’t understand why it looks so different from what they’ve expected. Fluorescence is one of the risky factors that can cause this situation. It sounds scary, which is why it’s so essential to understand this factor. Make sure to keep reading.

Not sure which diamond is right for you? You can contact me here.

Lab-grown diamond fluorescence

Unlike natural diamonds, lab-grown diamonds are grown in a controlled environment, which allows the lab to avoid any fluorescence. This is why 99.9% of the lab-grown diamonds you see are graded as “Fluorescence: none.”

As a side note, by using unique equipment that exposes the diamond’s fluorescence, a lab can determine whether a diamond is lab-grown or natural. Yet even if the fluorescence is visible under this machine, it has zero effect on the lab-grown diamond’s beauty in a regular daily environment.

Diamond fluorescence and lighting

After realizing how UV light affects diamonds, gemologists initially came up with a lighting standard for color grading that did not have a UV component. The grading continued until 2008 when the standards changed. The new criteria to grade diamond colors require the diamond to be under daylight, an equivalent light bulb with a UV component.

The UV component is approximately 30 microwatts/cm2 for diamond grading. Basically, the lab mimics a bright sunny day in summer to see how the diamond looks in a daily environment, with and without UV rays. This means that fluorescence does not make your diamond shinier. For instance, if you stay indoors, closer to a light bulb, the diamond appears dull than its color grade.

Is there a diamond fluorescence grade?

The GIA does not grade fluorescence as one of the main factors, aka the 4cs: color, clarity, carat weight, and cut. However, they do consider diamond fluorescence as an identifying feature. Their grading reports classify diamond fluorescence according to its intensity compared to master stones used in the lab. The fluorescence intensity levels include:

  1. None: No effect at all
  2. Faint: The fluorescence is very minimal and has almost zero effect on the beauty of the diamond. Most likely that we won’t notice any difference with the naked eye.
  3. Medium: The fluorescence is minimal but may be visible to the naked eye, depending on the color grade and the environmental lighting conditions.
  4. Strong: The fluorescence is visible to the naked eye and affects the beauty of the diamond.
  5. Very strong: The fluorescence is visible to the naked eye and strongly affects the beauty of the diamond.

Not all diamond fluorescence blue

The most common glowing color caused by fluorescence is blue; however, this is not the only color that diamonds shimmer in. some diamonds glow in different colors.

A yellow fluorescence is very common as well. Moreover, it can affect the actual color grading process if it’s not done right. Diamonds with strong yellow fluorescence may be positioned in a lower color grade than it looks in a UV-free environment. When you spend most of the time indoors, the diamond will look better because the fluorescence doesn’t make the diamond shimmer.

Some diamonds also have fluorescence that shimmers in rarer colors like magenta, green, and red. Unlike blue and yellow, strong fluorescence in these colors makes the diamond look darker. When the fluorescence is lower (faint-medium) in these colors, it won’t affect the color grade of a diamond. This is because they contrast with yellow.

Will diamond fluorescence make a yellow diamond look whiter?

In low color grades such as I to M, diamonds show a yellowish tint that is visible to the naked eye. However, combining such a diamond with a medium-strong blue fluorescence can boost its color and make it appear brighter and whiter. The blueish glow can hide the yellowish tint when the diamond is under UV light, like natural daylight.

In general, a diamond with a low color grade is more affordable. Still, since the sellers know that the fluorescence can make it appear whiter, they can ask for a slightly higher price per carat than similar diamonds without fluorescence.

The contrary is also true. High color grades such as D to H won’t look good when combined with medium-very strong fluorescence. It can cause an oily and hazy appearance and affect the brilliance and sparkle of the diamond. However, not all diamonds with a fluorescence look oily though they cost less than diamonds without blue fluorescence. If you come across a diamond with an H+ color that has some fluorescence that doesn’t affect the beauty at all, you can enjoy the discounted price and get a good deal. That being said, with nearly-colorless and colorless diamonds, I’d stick to faint-none fluorescence to play on the safe side.

Can an average person tell the difference?

The GIA (gemological institute of America) has conducted an intensive study on the effects of blue fluorescence on diamond appearance. They screened many diamonds and grouped them into four groups, each with six diamonds. Each set represented a different color grade of E, G, I, and K. all the diamonds in the same group were similar in all aspects apart from the intensity of the blue fluorescence. Trained professionals, diamond graders, and average persons observed the diamonds in a regulated environment to judge their appearance.

The institution came up with the following observations; the average observer representing the large public jewelry consumers, and no methodical effects of blue fluoresce on the face-up appearance of the diamond set were identified. The diamond graders and professionals did not constantly agree on the effect of fluorescence moving from one diamond to the other.

In conclusion, the blue fluorescence had an insignificant effect on the face-up appearance of diamonds in color grades of D through J, diamonds in the colorless or near-colorless range. There is an exception of a minimal improvement in rare cases of very strong fluorescence intensity.

Cloudiness in fluorescent diamonds

One of the significant disadvantages of strongly fluorescent diamonds is cloudiness. Though the cloudiness effect does not occur in all fluorescent diamonds, it is crucial to get a closer look at the diamond before purchasing it.

Milky or cloudy effects are usually found in medium-very strong fluorescent diamonds. It also occurs with medium fluorescence diamonds combined with high color grades (H+). In rare cases, it can be found in diamonds with faint fluorescence.

Generally, cloudiness is usually found in higher color grades. As a buying tip, it is wise to totally avoid medium and strong fluorescent diamonds in color grades D, E, and F.

Recommendations for diamond fluorescence

To be perfectly candid, you won’t easily notice a slight change in color due to the UV fluorescence in diamonds. However, you should avoid diamonds with a very strong fluorescence because they may have a noticeable shift.

If you are interested in fluorescence, I recommend aiming for M-I color grades. That is because those with strong fluorescence might appear slightly off-color in non-UV-emitting lights. On the other hand, medium fluorescence will give you a discount and most likely won’t hurt its color.

For the highest color grades, make sure that you check the diamonds whose fluorescence ranges from strong to medium. They most likely will have an oily or milky appearance. Make sure to buy the diamond from a place that allows returns and replacements. This way, if you find out that you are not happy with the fluorescence of the diamond in your daily environment, you’ll be able to replace it.

Specifically, milkiness is highly unlikely in H and G color diamonds, and fluorescence can offer a significant discount. At the end of the day, it is upon you to decide if you would like a non-fluorescence or fluorescence diamond in your engagement ring. It will all depend on your preference.

6 Tips on diamond fluorescence

  • When shopping for a diamond, ask the seller to inspect it under daylight and UV light. Try to place the diamond under multiple light sources. Pay attention to the color of the diamond from the top view and see if it turns to a different color. Check the diamond from the side view as well. Although we watch the diamond from the top view 99% of the time, the side view shows less brilliance; hence it’s easier to notice its actual color. If the diamond doesn’t change its color, yet it’s graded as faint-medium and offered at a discounted price, it might be a good deal.
  • I highly recommend buying diamonds only from retailers that offer returns and replacements. This way, if you buy a diamond with fluorescence, inspect it in your home light environment and find it’s not what you wished for, you can return it and feel safe that you are in good hands.
  • Keep in mind that faint fluorescence has almost no effect on the diamond, yet you can get a discounted price. If you find a beautiful diamond with faint fluorescence for a reasonable price, it might be a good deal. Not sure? Contact me here.
  • In lower color grades such as M-I, fluorescence can enhance the total appearance of the color and make it appear whiter. Check the diamond under multiple light sources to ensure the diamond looks relatively colorless both from the face-up and the side-view.
  • In higher grades such as H-D, especially F-D colorless, look for a good discounted price. Usually, I recommend avoiding medium-strong fluorescence, but it’s up to you, and every case is different. You might come across an E color that looks like a J-H when combined with medium fluorescence. Naturally, such a diamond is worth much less. If you find an E color that still looks colorless, even when it has fluorescence and is offered at a discounted price, it might be a good deal.
  • Something else worth noting is that it is upon you to decide the kind of fluorescence of a diamond that is bad or good. It is down to your preference, and you should go with what pleases you most.

With these tips, you will get a diamond with the right kind of fluorescence that will be good for you.

How does diamond fluorescence impact cost?

Medium-strong fluorescent diamonds typically come with a discounted price, about 10-15% less than the faint to none ones. It means you will save a lot by going for fluorescent diamonds. Keep in mind that some diamonds do have some fluorescence, yet it doesn’t affect their look at all. Coming across such a diamond with a reasonable price can be an excellent value for money.

Conclusion: Is diamond fluorescence good or bad?

Well, what one must know is that fluorescence is neither bad nor good. The beauty of a diamond lies in the eyes of the beholder. Some people perceive fluorescence and others don’t. You may fall in love with the bluish glow or prefer to see the actual color of the diamond.

For those who are looking for a diamond with bluish fluorescence, they should take time and review it under different kinds of lighting. For instance, you should expose it to natural light and note its effect. Then compare to other diamonds of the same color and how they behave under the same light. Be keen and note if there is any difference.

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