How To Tell If A Diamond is Real: 11 Tests You Can Do Right Now

diamond engagement ring

For many of us, buying a diamond is an emotional purchase, and is something that we really invest in and dedicate to that one special person. It only makes sense that you need to know whether it's real or not before committing yourself to a stone. With that said, you’re probably wondering how to tell if a diamond is real or not.  

These days, many "fake" diamond counterparts can be easily mistaken for a real diamond. There are plenty of natural gems with a strong resemblance to diamonds such as white topaz, white sapphire, and white zircon. 

If you're in possession of a diamond ring and are questioning its authenticity, then it's recommended that you seek out advice from a reputable jeweler. But if you're in a hurry, here are simple tests that you can use at home to tell if your stone is the real thing or a fake.

How to know if your diamond is real with home testing methods

Before trying out the options below, experts advise doing your homework. There are several diamond substitutes on the market, with some having a value of their own while others aren't worth much. It's also important to know the difference between mounted and loose diamonds. A loose diamond, or one that hasn't been mounted in a setting, is easier to test, for both its authenticity and determining if it has any flaws. 

Mounted diamonds' mounting can hide potential cracks and chips, and can also reflect light into the diamond, making it difficult for anyone but reputable jewelers to assess the stone's color or clarity. If you're planning to purchase a mounted diamond, you might want to ask the jeweler to remove the stone first, so that it can be inspected while it's loose. 

The Fog Test To Determining If Your Diamond Is Real

A quick and easy way to tell if your diamond is real or not — put the stone in front of your mouth and fog it up with your breath. If it clears up after a second or two, then it's real, but if karat stays fogged for three seconds or more, then you're looking at a fake. The reason for this is that diamonds disperse heat instantaneously, making it impossible to fog up. Before trying this test, make sure that your diamond is clean without any oils present. 

Water testing your diamond

This is probably one of the easiest ways to determine whether your diamond is real or not, however, it is not conclusive. Get a glass full of water and simply drop your diamond into the glass. If the diamond is real, it will drop to the bottom of the glass due to the high density of the stone. If it's a fake, it will float on the surface of the water. Unfortunately, not all fake diamonds float in water, so you might want to use another one of the techniques here.

How to tell if your diamond is real using a magnifying glass

Using a magnifying glass, hold up your diamond and look for imperfections within the stone. If you're unable to find any, then it is most likely fake — a majority of real diamonds will have flaws, which are referred to as inclusions. While there are flawless diamonds out there, they are either very pricey or lab-created. That being said, don’t throw away the stone after this because you may have a flawless, very valuable diamond on your hands. 

Using a black light to see if your diamond is real

For this one, you'll need a black light. Once you get it, turn off the lights in your home and place the diamond under the UV light. Wait for its reaction and observe the color it reveals; most diamonds will emit a blue-colored glow but not all of them — some diamonds don't glow under UV light. If instead, you see a slight green, gray or yellow fluorescence, then this usually means that the gem is not a diamond. Keep in mind though that this is not a conclusive test and not all diamonds will reveal a blue color, so it's best to have a diamond expert to use their advanced equipment to test the stone. 

How to tell if your diamonds real using a loupe

A loupe is a small magnification device used by jewelers to see minute details up close. Most jewelers use loupes to inspect diamonds for their class and clarity. If you don't have one then you're in luck, as Amazon has a huge selection of loupes at reasonable prices. Alternatively, a diamond professional will have access to a loupe, which they will then use to look for blemishes and imperfections within your diamond. While a fake diamond can be perfectly structured, a real diamond has some qualities that can't be faked — a diamond will have small imperfections called inclusions. 

Check your diamonds mount

If your diamond is already placed in a ring, check the type of mount that's been used. It should only be set in high-quality jewelry such as platinum, white gold, yellow gold, pave or halo setting, and side-stone setting rings. To determine if the setting is truly as it is described, look inside the ring for markings. The markings PT and karat refer to platinum, while notes such as 10K, 14K, and 18K indicate the type of gold used. If you see numbers such as 585, 770, 900, and 950, this indicates that platinum or gold was used. If you see a "C.Z" marking, however, the gemstone used is actually cubic zirconia and not a real diamond. And if you see the markings for silver such as .925 or the Argentium Silver marketing, it's most likely fake.

Perform the scratch test to determine if your diamonds real

Once a widely used technique to determine the hardness of a gem's mineral, the scratch test involved scraping the loose gemstone along a mirror to see if it would scratch the stone or the mirror. And while diamond is made from extremely strong materials, fakes such as moissanite, cubic zirconia, and even black spinel are also scratch-resistant and durable. It is because of these gems that the scratch test is no longer accurate. It's better to look at other techniques such as having the diamond inspected with a loupe. 

Check your diamonds transparency

person holding a diamond

Before performing this test, make sure that your diamond is clean. To test the diamond's refractivity, place the stone on its flat side onto a piece of newspaper with lots of lettering. Make sure to use bright lighting and that no objects are casting a shadow on your diamond. If you can read the letters from the newspaper — whether they appear blurry or not — then the diamond is fake. But if the diamond is real, its facets will refract light in multiple directions instead of a straight line. Because of this, you won't be able to see through the diamond to make out the letters on the paper. 

Using fire to test your diamond

Another method to determine if your diamond is real or fake is to use a lighter to light the stone for about 30 to 40 seconds before dropping it in cold water. If it's a fake diamond, it will shatter to pieces but a real diamond won't have a reaction to it. This is because weaker materials will not be able to handle the rate at which it expands and then contracts due to the heat of the fire. Real diamonds, however, have been formed under intense pressure and heat underground from billions of years ago. While this is a more accurate way to test a stone's authenticity, it can be dangerous to use fire, so be sure to use proper safety measures and use heat-resistant gloves when handling the diamond. 

Using a diamond scale

While not everyone has access to a diamond scale, you can be sure that your local diamond jeweler will. If the diamond is fake, it will weigh more than a real diamond of the same shape and carat. This is because cubic zirconia weighs about 55% more than an actual diamond. To perform this test, you'll need to have two stones with you; one diamond and one fake that has the same shape and carat.

Observing your diamonds sparkle to determine if it’s real

A sparkle test is quick and easy to do since all you need are your eyes. Simply hold your diamond under a normal lamp and observe the bright shimmers of light bouncing off the diamond. A real diamond provides an exceptional sparkle since it reflects white light extremely well. In addition, diamonds can also reflect fire or colored light in a beautiful display. Compared to a stone like Cubic Zirconia, you'll be able to see a huge difference in the white and colored light sparkle. A Cubic Zirconia gives off a notable rainbow of light. However, it is advised that you don't use this as your only testing method, so try and use the other methods highlighted here. 

Tips for how to know if your diamond is real

isolated diamond on a tweezer

Many of the tests outlined here, such as the fire test and the fog test can help to confirm whether your diamond is real or not. But because of the complexity of synthetic gemstones, we highly recommend combining a few of these tests together to really get an answer to your burning question of whether you have a real diamond or not.  

If you're still unsure, it's best to see a jeweler or diamond expert to review the pieces you have. These experts are highly trained to be able to discern a fake diamond from a real one. Thankfully, any diamond you purchase will come with a legitimate AGS or GIA certificate, so all you need to do is to make sure that the diamond matches the certificate. You can also ask for a grading report when purchasing your diamond, so you can put your mind at ease, at least until you decide to pop the question.