Skip to Content

Do Fake Diamonds Glow Under Ultraviolet (UV) Light?

Do Fake Diamonds Glow Under Ultraviolet (UV) Light?

You don’t have to be a jewelry expert to know a thing or two about diamond fluorescence.

If you’re an owner of a diamond and you value your possession, it’s time to brush up on this particular topic. More precisely, we’ll be focusing on answering the famous question: Do fake diamonds glow under UV light?

If you turn it on and your gem doesn’t glow, you’ve got a fake one!

This is just scratching the surface, though. There’s much more you can learn about diamond fluorescence besides testing. We’ll talk about price, how it affects the gem, and so on.

So, if you’re curious about your diamond (not) showing fluorescence, keep scrolling.

Diamond Fluorescence 101

First and foremost, let’s pick up on some basics regarding diamond fluorescence. What is diamond fluorescence and how’s it determined?

Diamond fluorescence is simply the effect that the UV light has on your gem. Simply said, when you expose your diamond to blacklight (UV light), it will show off a certain color.

In most cases, you’ll be looking at blue, but know that that’s not always the case.

The critical thing to remember here is that not all diamonds are fluorescent. According to statistics, only 30-35% of gems glow under UV light.

Now that we’ve cleared that up, let’s talk about “levels” or types of fluorescence within a diamond. Generally speaking, there are five types of diamond fluorescence that can be easily determined. 

They are:

  • None fluorescence: diamonds that won’t glow under UV light.
  • Faint fluorescence: diamonds that show slight fluorescence.
  • Medium fluorescence: diamonds with fluorescence.
  • Strong fluorescence: diamonds that show strong fluorescence.
  • Very strong fluorescence: diamonds with extremely vivid fluorescence.

We couldn’t help but ask ourselves, “what causes diamonds to glow under blacklight?”. Luckily, we have the answer to that as well, and it’s pretty simple.

Science. The chemicals contained in the diamond’s crystalline structure are responsible for absorbing and re-emitting the energy in the form of light, a.k.a fluorescence.

We’re talking about elements such as aluminum, nitrogen, and boron; all present in the diamond’s crystalline structure.

Now that we’ve got your attention, it’s possible that this thought has crossed your mind: Do both lab-grown and natural diamonds glow under UV light?. If so, the answer is yes

Both natural and man-made diamonds will glow once you put them under UV light. There’s actually a similarity in the color that they show, which is blue. This is due to the submicroscopic structure of the crystal.

But wait, do all diamonds reflect blue? The answer to this one is no.

Although we’re used to seeing blue fluorescence, it’s not the only color you will see once you put your diamond under the blacklight. The second most common color you can see is actually yellow. And if you notice this instead of blue, you have a lower-grade diamond.

Besides blue and yellow, you’ll also see green, red, or magenta in some diamonds. However, these are rare cases, and it depends on the entirety of your lighting.

Does Fluorescence Affect the Price?

It’s unanimous; diamond fluorescence has an enormous impact on its price. You’ll understand why as soon as we go over the facts once again, so here they are:

Only 30-35% of diamonds are fluorescent, but you knew that already. However, did you know that strong and very strong fluorescence in diamonds can reduce their value by 15-20%?

Yes, fluorescence is a good thing, as long as there’s not too much of it.

Monetary-wise, you’re looking at a $2,000 difference. 

From a seller’s perspective, this is not looking very well. Also, if you were thinking of reselling your diamond, you should think twice before you act on this decision.

Learn More:

The Pros and Cons

What are the pros and cons of having a diamond that glows under UV light? Here’s how we see it.

The first advantage of this is that fluorescence can highlight the color of your diamond in specific lighting, making it even more attention-grabbing than, for example, a gem with no fluorescence. 

Of course, remember that you are choosing a diamond with medium fluorescence, which would be the “perfect measure” for your gem.

The next thing is the price range, but this time, from the buyer’s side. If you are not a  jewelry collector or someone who bothers with details too much, you’ll be relieved to find that diamonds that have strong fluorescence are less expensive.

On the other hand, this can also be a disadvantage, especially if you are the one behind the stand selling the diamond. Diamonds with strong and very strong fluorescence will appear “cloudy.” 

This “cloudiness,” or “fogginess,” as some like to call it, is what drives the buyer away.

For some, this will be simply unattractive and not a good enough reason to decide to buy this diamond. Also, keep in mind that this is very visible in daylight.

Diamond Fluorescence Test

The answer to the question “do fake diamonds glow under UV?” can be revealed by relying on the UV test.

Yes, testing to see whether your diamond will glow under a blacklight is an effortless way to find out whether you’ve got a fake or a real gem in your jewelry possession.

If you’ve got UV lighting in your home, now’s the perfect time to put it to good use. Take your UV light and turn all of the other lights off.

Put your diamond under the UV light and turn it on. Pay close attention to the color it shows. If you’re seeing blue, yellow, green, or even brown, you’re safe – you’ve got a good one.

However, if your diamond doesn’t glow, there’s a good chance that you’ve bought a fake one. Fake diamonds will not glow under UV light.

Before you flip out over your diamond not showing color, remember that there are REAL diamonds that are not fluorescent. This is just a home version of checking your gem.

For verified checks, you can turn to other tests.

Other Tests You Can Try

Speaking of tests, putting your diamond under ultraviolet light is just one way to check your game. For those in doubt, here are a few more methods:

The Water Test

Take a glass and fill 3/4 with water. Take a loose diamond that you have, and drop it into the glass. If your gem sinks, it’s real. If it floats, it’s fake.

For clarification, diamonds are characterized by high density, so there’s no way a real diamond will float back up.

The Heat Test

If you’re eager to test your diamond, here’s another test that you can try by using a lighter, some gloves, and a glass of water.

For this experiment, make sure that you’ve got some heat-resistant gloves on. Put them on and grab a lighter and your diamond. Light up the fire and put your diamond close to it.

Hold it like that for approximately 30-40 seconds.

After you’re done, drop your diamond into the glass. If it shatters immediately, it’s made from weaker material, and, more importantly, it’s a fake. 

A real diamond will not react to heat.

Another characteristic of diamonds is that they are heat-resistant so that a real gem will have no problem being under the fire of an ordinary lighter. Also, a real diamond should sink in water.

The Puff Test

The following test does not require any equipment except your attention and full concentration.

The “puff test” is done by taking your diamond. It can be a wedding ring or a necklace piece and put it under normal lighting for better observation.

Breathe a few times on your diamond and wait for the reaction. The puffs of air that show on your diamond are the key. If they disappear right away, you’ve got a real deal.

If it takes the puffs of air to disperse for more than 30 seconds, you’ve definitely got a fake diamond in your possession.

The explanation is simple, too. Diamonds conduct heat very well, so dispersing it also happens quickly.

The Sparkle Test

The “sparkle test” does not imply additional equipment except for your eyes.

Again, you’re going to need your diamond and standard lighting. Put your diamond under the light and watch out for its sparkle.

A real diamond reflects white light exceptionally, and you’ll see a beautiful shine if you look a little closer. Also, real diamonds can reflect different colors, but the emphasis is on the clarity of the “sparkle.”

Even if you are not a professional, you will be able to see the difference in sparkle between a real and a fake diamond.

Related Read: Does A Real Diamond Sparkle Rainbow?

The Diamond Tester

If you’re not a fan of DIY versions of diamond testing, you can always turn to concrete options such as turning on a diamond tester.

What is a diamond tester, and is it the same one we see in movies?

Well, close enough. A diamond tester is a small device used to test your diamond’s authenticity and the materials for electrical and thermal conductivity.

In short, it’s like a lie detector for your diamond.

These diamond testers are all available online, and you can very quickly get the hang of how to test the two: electricity and heat.

Learn More: How Does A Diamond Tester Work?

Leave It To The Professionals

The last option would be to leave it to the professionals, of course.

Suppose you’ve bought your diamond elsewhere and not in a legit jewelry store; it’s possible to feel suspicious about its authenticity. Maybe the seller didn’t seem legit, or the condition of your diamond is making you doubt yourself.

Either way, you can always take it down to the store to get it checked out by the professional himself.

Our Take on Diamond Fluorescence: Is It Good or Bad?

Here’s our take on diamond fluorescence:

With interested buyers, we would recommend that they still go for it and buy fluorescent diamonds. After all, it’s a better choice than non-fluorescent ones, that’s for sure.

When you put it like this, it sounds a bit general. When it comes to real-life situations, though, and it’s just you and the diamond, you should go for the one with medium or strong fluorescence.

The non-fluorescent is not a superb choice, and you don’t want to go for the “very strong” option because it’ll make your diamond look cloudy. 

That’ll take a toll on its appearance mostly.

Also, take it from us. Buying diamonds online and assessing fluorescence simultaneously is not the way to go. There’s just too much uncertainty with online shopping.

If fluorescence in a diamond is something that’s important to you, and you don’t want to buy a fake one (obviously), don’t be lazy to make a trip to the jewelry store. 

Leave the online option for scrolling and comparing prices.

Wrapping Up

We gave it our best to answer the question of “do fake diamonds glow under UV light,” and we think we’ve covered the essential parts. Let’s just briefly go over everything once again.

In layman’s terms, diamond fluorescence refers to the effect that ultraviolet light has on your diamond. It can be traced back to science, but you shouldn’t concern yourself with science.

The critical thing to remember is that this is a way to test whether you’ve got a real or fake diamond in your possession. And you’ve guessed it: fakes don’t glow under UV light.

When buying a diamond, fluorescence can be both good and bad – depending on how much your diamond shows. You don’t want a non-fluorescent diamond, but intense fluorescence might make it look cloudy.

We recommend going with the “medium” option, and we can guarantee you’ll be satisfied with your choice.

Related Read: Can Ultraviolet (UV) Light Destroy A Diamond?

Customize Your Dream Ring. Click Here To Try It Now!