back to Everything Diamonds

How to Tell if a Diamond Is Real: An Extensive Guide

by Haley Anhut
Last updated on September 16, 2023
Woman wearing stacked diamond bands.

When you’re shopping for a diamond ring, you might be wondering how to tell if a diamond is real. How do you know if your gemstone is a true diamond or a fake diamond? The answer is simpler than it seems!

There’s actually no such thing as a “fake” diamond. All diamonds are “real” or genuine. This includes both diamonds mined from the ground and diamonds grown in a lab. Otherwise, a fake diamond is actually a simulated diamond, also called an imitation. Therefore, all diamonds are real diamonds regardless of their origin.

What Is a Real Diamond?

Real diamonds are a crystallized form of pure or nearly pure carbon. They are the hardest substance on Earth. According to the Federal Trade Commission, both lab grown and mined diamonds are real diamonds made of carbon but in a crystallized form. All real diamonds have a specific refractive index and no other material can duplicate it. They also have unique chemical and optical properties unmatched by any other material.

Various rings made by Clean Origin.
Rings by Clean Origin.

Cubic Zirconia and Other Fake Diamonds

Anything other than a real diamond is a fake diamond or imitation. Fake diamonds may look like a diamond to the naked eye, but they will be made from something else. 

Fake diamonds will be softer than real diamonds. If a diamond is real, it will also have a different refractive index (a measurement of the light being refracted to the eye) than a fake diamond. They may be made of a variety of other minerals like moissanite, white sapphire, cubic zirconia, white topaz, or even glass.  In keeping with FTC guidelines, diamonds from the ground need to be called “diamonds” while “lab grown diamonds” have to be identified as lab grown. Even with a slightly different name, a lab grown diamond is still a real diamond.

Over the years, many jewelry companies have created stones that simulate a natural diamond using weaker materials. These are often less expensive than real diamonds but don’t have the chemical integrity of authentic diamonds.

Is a Synthetic Diamond a Fake Diamond?

Lab grown diamonds have the same properties as real diamonds--How to Tell if a Diamond Is Real.
Mined and lab brown diamonds have the same properties.

A jewelry store may also use the word “synthetic” to describe some diamonds or other gems.  However similar they sound, “synthetic” and “simulated” aren’t the same thing.

Any type of synthetic gemstone has the exact same chemical properties as its natural counterpart. For example, lab grown diamonds are synthetic diamonds even though they have the exact same properties as real diamonds. The same goes for lab grown sapphires and other precious lab grown stone matches.

Simulated gemstones, like cubic zirconia and white topaz, look like their natural counterparts but have different chemical makeups. These stones can be made of any material. Most simulated gemstones have little to no value in the marketplace. No matter their name, they are not diamonds.

Lab created diamonds, however, have the same chemical properties as natural diamonds. The only difference between natural and lab created diamonds is that one is mined and the other is grown in a lab. Lab grown diamonds can come in the same shape, color, and shine as natural diamonds; and you have the added benefit of the same quality ring at up to 40% less the expense.

How to Tell if You Have a Real Diamond

Diamond bands and earrings.
Diamond bands and earrings.

Not all fake diamonds are obvious fakes. It might be hard to tell if it is an actual diamond or a white sapphire, for example. While a jewelry collector may not see the difference between real and fake diamonds with the naked eye or a magnifying glass, a trained jeweler can. Most consumers can tell a real diamond from an imitation by learning how to tell the difference.

Sometimes, you can quickly tell if a diamond is real by using a diamond tester or magnifying glass. When in doubt, be sure that the name and certification say that your stone is a genuine diamond with no qualifying brand. Both lab grown and mined diamonds will test as real because they both are. You’ll need highly specialized equipment to tell whether a diamond is lab grown or mined. Fortunately, diamond imitations are much easier to spot.

UV Light Test

When verifying a diamond’s authenticity, a professional jeweler might test it under UV light. A genuine diamond will have a distinct blue-colored glow, while a fake one may not have this coloring. However, it’s important to note that the UV light test isn’t foolproof, though most diamonds will emit a blue fluorescence.

Sparkle Test

Experts use the sparkle test to evaluate a diamond’s beauty by examining its brilliance and fire. This involves exposing the diamond to different light sources and observing how it reflects and refracts light. A genuine diamond will display a magnificent play of light, while lower-quality diamonds or diamond simulants may not have the same captivating sparkle and brilliance.

Dot Test

A simple and efficient way to spot some fake diamonds or diamond simulants is the dot test. First, place the diamond face down on a white sheet of paper or a piece of newspaper. Then, draw a tiny dot with a pen or marker on the paper, directly above the diamond’s point. If you can see the dot through the diamond, it’s probably a fake diamond, as real diamonds have high refractive properties that usually make the dot unclear. Please note that this test is not a conclusive way to determine the genuineness of a diamond, so it is recommended to seek professional evaluation.

Vintage-inspired rings.
Vintage-inspired rings.

Fog Test

A quick and easy way to tell if a diamond is real or fake is through the fog test. To do this, simply breathe hot air onto the diamond’s surface and observe the condensation. If the fog disappears quickly, the diamond is probably authentic. On the other hand, if the fog lingers for a long time, it could indicate that the stone is a fake or a diamond simulant. It may be hard to test black diamonds in this fashion.

Float Test

Another way to test a diamond’s authenticity is through the float test. To conduct this test, you will need a loose diamond and a regular-sized drinking glass filled with water. Gently place the diamond into the water and observe its behavior. Typically, fake diamonds will float due to their lower density, while genuine diamonds will sink to the bottom due to their high density. Although this method is not 100% accurate and may not work on all diamonds, it is a simple way to eliminate the possibility of a loose diamond being fake. Note that mounted and loose diamonds may behave differently during this test, and it should not be used on mounted diamonds.

How to Tell if a Diamond Is Real: Authentication Red Flags

Be wary of a large real diamond that isn’t set in white or yellow gold or platinum.  If a diamond is real, it will most likely have a setting with one or more of these precious metals rather than sterling silver. Anything larger than a half-carat diamond set in something other than yellow gold, white gold, or platinum is reason to take a second look.

If you have any doubts at all, it’s worth it to take a second look at your diamond. Make sure that your diamond comes with a certificate from a recognized gemstone laboratory such as IGI or GIA

You can also shop with confidence at Clean Origin. All loose diamonds and diamond jewelry from Clean Origin come with a certificate from IGI. And the certificate number of each diamond is laser-engraved on the girdle as well.

An At-Home Test for How to Tell If a Diamond Is Real

Diamond solitaire rings.
Diamond rings.

If you want to test your gemstone at home to determine if you have a real diamond, the most reliable way to check is by using a diamond tester. Diamond testers determine if a diamond is real by performing a heat test with a thermal conductivity probe.

Heat moves through different materials at different speeds. Therefore, heat will move through a diamond in one specific way if the diamond is real. You’ll be able to distinguish between real and fake diamonds using the results from the heat test. If your gemstone is a diamond, it will disperse heat rapidly.

At-home diamond testers are available through some online retailers at a variety of prices. However, you should always consult a diamond professional or reputable jeweler if you have any questions about whether your stone is real or fake.


Diamond wedding ring set.
Wedding ring set.

If you want to know whether or not your diamond is real, there are a number of ways to authenticate your stone. Either at home or with a jeweler, you have options when it comes to testing your jewelry. Here are a few FAQs about diamond authenticity.

How Can You Tell if a Diamond Is Real or Cubic Zirconia/Moissanite?

Both cubic zirconia and moissanite have different refractive indexes than diamonds. These two diamond simulants, like others, also have different chemical properties from real diamonds.  However, these are not things that most people can detect easily at home even with a magnifying glass. Seek advice from a professional if you’re not sure.

Can You See a Difference Between Mined and Lab Grown Diamonds?

A lab grown diamond is real, just like a natural diamond is real. While there are flawless diamonds out there, both lab grown and natural diamonds come in the same degrees of clarity, color, and cut.  You can’t see any differences with the naked eye. Even a jeweler cannot tell the difference by sight.  Only the use of very specific lab equipment can reveal a real diamond’s origins.  Gem labs like GIA or IGI would have the right equipment, but your local jeweler likely won’t.

A scratch test can damage a diamond.
A scratch test can damage a diamond.

Can I Determine if a Diamond Is Real With a Scratch Test?

This is a tricky question. You can use a scratch test to determine your diamond’s authenticity. However, you probably shouldn’t.

While diamonds are the hardest mineral on earth, they can also have their polish damaged by a scratch test. The diamond itself may chip if struck at just the right angle.  This test is also not entirely accurate, as a diamond can scratch glass, but so will some other materials. Once again, if in doubt, talk to your local diamond jeweler.

Should My Diamond Glow Under a Black Light?

This would only be true if the diamond has a relatively high degree of fluorescence.

Should My Diamond Float in Water?

No. A loose stone will sink in water if it’s a diamond. However, this is not a valid test of whether a loose gemstone is or is not a diamond because other materials will also sink. On the other hand, some imitation diamonds float.  Therefore, if it floats, it is not a real diamond. If it doesn’t, it may be a diamond.