Real vs. Fake Diamonds (How to Tell If A Diamond Is Real)

With a number of really good diamond imitations out there, you might be wondering whether all the diamond jewelry that you own actually contain real diamonds. After all, moissanites and cubic zirconia both make for very convincing diamond lookalikes. We’re not saying you have been cheated, but a little bit of wariness is always a good quality to have.

In this guide, we’ll take a look at a number of practical methods you can use to determine if a diamond is actually the real deal. But remember, while the methods in this guide will prove useful, you should not consider them to be the be-all and end-all of your gem’s authenticity. If doubts persist, you should always reach out to a diamond expert with the right tools for the job.

That being said, let’s take a look at the methods available.

Simple Tests To Tell If A Diamond Is Real

Once again, we stress that the ultimate way of being sure that the gemstone you have in your hands is a real diamond is to get in touch with and use the services of a jeweler or a diamond expert. But if you want to test your stone’s authenticity yourself, there are several tests you can do at home that will serve as a good starting point.

1) The Sparkle Test

To start with, a test that requires no equipment: the sparkle test. Hold the diamond under a white light and see how the light reflects off of the stone. If you see bright white light bouncing off the diamond with colorful plays of light, we’ve got good news for you. You are likely holding on to a diamond.

Because a real diamond is very reflective, it reflects white light exceptionally well. A real diamond held under white light should display a brilliant sparkle. The diamond will also display colorful flashes of light — known as fire — under white light. Light reflected by other gemstones like cubic zirconia or moissanites don’t come anywhere near the level of brilliance displayed by diamonds.

2) The Water Test

If you’re still unsure about your diamond, you can always use the water test. This is simple enough: you take a drinking glass, fill it three-quarters of the way with water, and gently drop the stone in question into the water.

If it sinks, you’re cool. It could be a real diamond. If the gemstone floats — whether it’s at the surface or underneath it — you’re not cool. It’s a fake diamond. Because of it’s high density structure, a real diamond will always sink to the bottom. Anything that doesn’t sink is not a diamond.

3) The Heat Test

A little bit more complicated than the water test, the heat test is another way to test your diamond’s authenticity.

Get a glass of ice cold water. Don’t drop the diamond into it. Not yet, at any rate. First, you need to hold the diamond over an open flame (ideally using a pair of pliers or other similar safety equipment). After 30 to 45 seconds, drop the stone directly into the cold water.

If the stone is not a diamond, it will shatter. Because diamonds are incredibly durable — they are, in fact, among the strongest materials on the planet — they will not react to high heat at all. Diamonds will simply disperse the heat quickly and not be affected by the sudden change in temperature at all. But most materials used to make diamond imitations are not anywhere near as durable, and as such, they will outright shatter or at least get seriously ruined.

Obviously, if you don’t want to ruin your stone (even if it is fake) this test won’t really do you much good. But that’s no worry, because we’ve got more.

4) The Fog Test

Here is another simple, no equipment test. Hold the diamond in your hands and just breathe on it. Because of the moisture and heat in your breath, a light fog should form on the stone.

If that fog dissipates quickly, you’ve got a real diamond. As we mentioned above, diamonds are excellent conductors of heat and therefore disperse heat quickly. Any other material, and it will take several seconds for the heat to disperse.

5) The Scratch Test

If you’ve got sandpaper, you can have a go at this test as well. All you need to do is rub your diamond against the sandpaper (the gritty side, obviously). The sandpaper will have zero effect on a real diamond.

As we mentioned above, diamonds are one of the hardest materials on earth, which means that the sandpaper grit (which rates at only between a 7 to 9 on the Mohs scale most of the time) will do nothing to the diamond. While this method will weed out some imitation diamonds, you should keep in mind that sometimes, stones made of cubic zirconia or moissanites can easily pass this test as they are quite scratch-resistant as well. For those, you might have to perform some advanced tests.

6) The Newspaper Test

Place your diamond, flat side down, on a page of a newspaper. Or any piece of paper that has a lot of lettering. Make sure you are in a well-lit area and that there are no other people or objects casting a shadow on the diamond. Now, see if you can read the letters in the newspaper (or the book or whatever).

If you can read the letters, sorry. That’s a fake diamond in your hands. Even if the letters are blurry, the fact that you can see the letters at all will mean that the diamond is fake. Diamonds are very refractive, and when light strikes the angled surfaces on the lower half of the diamond (technically known as ‘pavilions’), the light is bounced and refracted through it’s top, flat surface. This means light does not travel through the diamond in a straight line, meaning you should not be able to read anything through a diamond.

7) The Dot Test

This is similar to the newspaper test, and in fact serves as a great alternative to it.

First, get a plain white paper and draw a small dot on it. Once you’ve got that done, the next steps are essentially the same as the newspaper test. Lay the stone on the dot, flat side down. Look straight down through the diamond. If you can see a circular reflection inside the diamond, it is fake. For the same reasons stated above, you should not be able to see the dot or a reflection of it when you look straight down into the diamond. If you cannot see the dot or a reflection in the diamond, then you don’t have to worry. Your diamond is real.

8) The UV Test

If you’ve got a UV light, it can also help you test your diamond in a simple but effective way. All you have to do is place the diamond under the UV light and see how it reacts to the light.

Most diamonds will reveal a blue fluorescence under a UV light, which means you’ll see the diamond emit a blue colored glow. If you don’t see blue, but rather see a slight green, yellow, or maybe gray glow, it means that the diamond is not real.

However, there is a catch with this method. The catch is that some diamonds do not glow under UV light at all. Which means that while this test can help you confirm a diamond (if it glows blue) or even reject it (if they glow a different color), if there is no glow, you can’t be sure about what you are holding in your hand. In such cases, your best bet is to reach out to a diamond expert or jeweler and have them use their advanced equipment to test the stone.

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Not So Simple Tests To Tell If A Diamond Is Real

Whereas the methods listed above are all simple enough that you can try them yourself at home, listed below are some expert tests that are used to tell if a diamond is actually a diamond or simply an imposter.

1) The Loupe Test

A loupe is a special magnifying glass that is used for all kinds of gemstones. Experts can use a loupe to peer at the diamond and determine if it’s real or fake.

Most often, mined diamonds will have tine, natural blemishes and imperfections (called inclusions) that indicate that the diamond is indeed real. Experts will also look for small flecks of minerals and slight color changes. If signs of small flecks of minerals and color changes exist, the diamond will more than likely be real.

Do note however, that while fake diamonds won’t have any inclusions in them, you can come across real diamonds that lack them too. These are rare flawless diamonds, and we do mean they are rare. Another factor to consider is that lab-created diamonds (more on them later) are also ‘real’ diamonds that won’t have any imperfections.

All of this means that while the loupe test is certainly useful, they do not necessarily have the final say on the authenticity of your gem. But no worries, there are other methods available.

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2) The Thermal Conductivity Test

Loupes are not the only tools at the disposal of a real diamond expert. (If a loupe is all they have, you’re probably dealing with a fake diamond expert.) Most gemologists and jewelers also have a nifty tool known as a thermal conductivity probe. 

As we’ve already mentioned, diamonds are effective conductors of heat. When they are warmed, diamonds will disperse the heat rapidly. Gemologists with a thermal conductor can see how well the gemstone disperses the heat to see if it’s real or not. If it disperses slowly, it’s not a real diamond.

However, there is one small hiccup with this method. Synthetic moissanite stones are often similar to diamonds in how they disperse heat, which means that this stone won’t give conclusive results if moissanites are in the mix.

3) The Weight Test

Diamonds can also be distinguished by their weight. Jewelers and diamond experts will have very fine tuned scales that can measure incredibly small differences in weight. Because the weight of a real diamond will be lower than fake stones like cubic zirconia, diamonds can be told apart from fake stones of the same size.

4) The Electricity Conductivity Test

With the right tools in hand, jewelers and gemologists can also use electricity to see whether the stone in question is a diamond or not.

Because diamonds conduct electricity better than other stones — even better than synthetic moissanite, which can fool the thermal conductivity tests — an electricity tester can provide a conclusive result as to whether or not you are dealing with a real stone. When subjected to the electricity conductivity test, a diamond will show conductivity while other stones like moissanite and cubic zirconia will not.

How To Differentiate Between Diamonds And Other Similar Stones

We’ve talked about how to tell if a diamond is real or not, but it’s equally good to know how to tell a diamond apart from other gemstones that might appear similar to a diamond to the naked eye.

1) Diamonds vs. Synthetic (Lab) Diamonds

Obviously, the closest ‘relative’ to diamonds are synthetic diamonds—as they have more or less the same chemical and molecular composition as real, natural diamonds. As synthetic diamonds have become increasingly more popular these days, it’s important to know how to differentiate between a real diamond and a synthetic one.

The only real way is to have the diamond reviewed by an expert. Because of how similar they are to real diamonds, without the help of experts using high magnification and conductivity tests, you won’t really be able to tell the difference yourself.

2) Diamonds vs. Moissanite

While synthetic diamonds have the advantage of sharing their chemical composition with real diamonds, moissanites do not. However, synthetic moissanites are easily the best imitators of diamonds right now.

Distinguishing between the two is impossible for the naked eye. Even at the hands of an experienced jeweler, the synthetic moissanite can cause trouble, as they can pass the thermal conductivity test. Electricity conductivity test is the only test that can catch a synthetic moissanite in the act. Jewelers may also use a powerful microscope to find inclusions and other small differences that set a diamond apart.

It’s also good to be wary of synthetic moissanites as they are becoming increasingly more prevalent in the market.

3) Diamonds vs. Cubic Zirconia

While cubic zirconia are used as diamond imitators, they’re thankfully one of the ones that are easily tested for authenticity. The sparkle test, for instance, can reveal that the ‘diamond’ in question is actually a cubic zirconia because cubic zirconia do not give off the same sparkle or fire given off by real diamonds.

Further, cubic zirconias reflect orange tinted light. They also weigh more than a real diamond and generally don’t have the inclusions that are present in real, mined diamonds. If further testing is needed, diamond experts can have the molecular qualities of the stone reviewed at a professional lab. With x-ray machines, you can see if the stone has a radiolucent molecular structure or a radiopaque molecular structure. Diamonds are radiolucent while cubic zirconia (and some other diamond imitators) are more radiopaque.

4) Diamonds vs. White Sapphire

While sapphires are commonly found in bluish hues, they are present in a wide range of colors including white. White sapphires, which look clear to the naked eye, can sometimes be passed off as diamonds.

However, white sapphires do not have the same signature sparkle that diamonds have, and they are not as clear internally. If the stone seems to be blurred—without distinct light and dark parts—and not quite brilliant, it’s likely a white sapphire.

5) Diamonds vs. White Topaz

White topazes can also look like a diamond at first glance. However, there are a number of characters that separate it from actual diamonds.

White topazes have a softer exterior, which means that unlike diamonds, their exterior is easily scratched. If you look at the surface of white topazes closely, you’ll see that they’ll have scratches on their surface that diamonds cannot have due to their durability.


Most of the tests we’ve described can help you determine if a diamond is real or not, even within the comfort of your own home. However, we have to stress the fact that the ultimate way to definitively know if your diamonds are real or not is to have them tested by a diamond expert or an experienced jeweler.

Today’s market is filled with a number of diamond imitators, both synthetic and otherwise, and the number and complexity of all these imitators means that you can’t quite be sure that what you have in your hand is a real diamond. Whereas diamond experts and jewelers are trained in the fine art of spotting fake diamonds.

If you want to buy a diamond that you know will be 100% authentic, you can always use our Buy A Diamond page. With the help of our in-house diamond experts, you can find the perfect diamond for you without any hassle. Our partners sell diamonds with verified certificates (typically via GIA) to ensure authenticity. That’s not to say you shouldn’t buy “fake” diamonds either, or lab-grown diamonds. It’s just important that you know what you’re buying so you get a fair price.

For any other questions you may have, whether it’s about the authenticity of a diamond you own or anything else, feel free to get in touch with us.