How to Tell if a Diamond Is Real

Asscher diamond.

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Diamonds are some of the most popular gems in jewelry. They bring brilliance, beauty and durability to engagement rings, necklaces, earrings and other designs. When buying diamonds or reviewing jewelry you may already have, you may be wondering if your diamonds are the real thing. After all, these classic gems have been imitated with many different materials and techniques over the years.

Popular diamond simulants include cubic zirconia, glass and moissanite. But despite some simulants coming close, nothing compares to the beauty of real diamonds.

So, how do you know that you’ve got the real thing? Unless you have a jeweler-grade diamond tester, you’ll need to try other techniques to determine if your diamonds are real. 

Blue Nile Sells Real Diamonds

Loose Astor diamonds.

Buying your diamonds and gemstones from reputable jewelers can give you peace of mind in the authenticity of your jewelry. You can rest assured that all the diamonds we sell are real, and we offer the paperwork to confirm this. 

If you’re purchasing diamond jewelry or loose diamonds from our online jewelry store or local jewelry showrooms, you can rest assured that you are purchasing genuine diamonds. We offer a wide selection of natural and lab grown diamonds that are accompanied by GIA diamond certification reports to verify their qualities and authenticity. 

Only natural and lab grown diamonds are real diamonds. All other diamond-like stones are considered simulants or their own gems. You can learn more about how lab grown diamonds are made to discover why they can receive IGI or GIA certification just like their natural counterparts. 

Techniques for Verifying a Diamond

You may be curious how to tell if diamonds purchased from other jewelry stores are real. The fastest way to check a diamond is to bring it to a jeweler who can test the stone with an electronic diamond tester tool. There are some at home techniques that can also help you determine what kind of gemstone you have. 

Fog Test

The fog test is one of the most popular techniques for how to tell if a mounted diamond is real at home. Simply hold the jewelry to your mouth and exhale on the stone like you’re trying to fog a mirror. A real diamond will dissipate any condensation from your breath quickly, while simulants will often stay fogged for a few seconds. 

Observing the Jewelry Setting

Your jewelry setting can tell you a lot about the quality of any gems in the piece. Typically, real diamonds will be set in metals like gold or platinum. If the jewelry is silver or gold plated, it will often feature a diamond simulant. 

The technique for determining diamond authenticity based on types of jewelry metal may not apply for custom pieces or vintage jewelry, so it’s important to check your gemstones with additional methods. 

Dot Test

This test for telling if a diamond is real measures the refractivity of your gemstone and is best done with an unmounted diamond. A real diamond is exceptionally refractive. For this test, draw a small dot on a piece of paper and place your diamond over the dot you’ve drawn. A real diamond will typically have high refraction that makes it difficult to see the dot through the stone. It is important to note that diamond cut plays a role in this test, and some diamonds with less-ideal cuts may be less refractive. 

Water Test

The water test is another technique for testing if an unmounted diamond is real. Both lab grown and natural diamonds are heavier than diamond fakes such as glass and quartz. This means that in general, a diamond will sink when dropped into a small glass of water. Glass and quartz, on the other hand, may sink slowly or even float. 

This isn’t a foolproof technique for how to tell if a diamond is real, though, as some simulants like cubic zirconia may sink quickly as well. 

Observing the Brilliance

The unique brilliance of diamonds is part of what has made these gems so popular for centuries. A real diamond usually has sparkle in shades of gray with intense light. Other gems like moissanite will have mainly rainbow sparkle. A highly polished jewelry-quality gemstone that has a dull sparkle is likely not a diamond. 

Top Questions and Answers About Diamond Testing

How can you tell if a diamond is real at home?

There are several ways to tell if a diamond is real with home tests. This includes the fog test, the dot test and the water test. Observing the stone’s brilliance and the jewelry it’s set in can also help you determine if you have a diamond. 

You can use your phone’s flashlight, or any flashlight, to test if a diamond is real. Simply shine the light on your diamond and look at how the light is dispersed by the stone. A real diamond will brilliantly show flashes of intense light and sometimes rainbows as well. 

A real diamond ring will usually be made from high-quality metals like platinum or gold. This is a good starting point for determining if you have a real gemstone. 

This is also known as the diamond fog test. With this approach, you use your breath to test if your stone gets foggy when you breathe on it. A real diamond will not stay foggy. 

Shine a flashlight closely on your stone. A real diamond will reflect white light and rainbow flashes. A fake diamond will likely not reflect much light. 

Some tests like the dot test and water test are best done with unmounted diamonds. But you can still inspect your mounted stone to tell if it’s real with other tests. Try the fog test or the flashlight test to learn more about your stone. Jewelers can test mounted stones using diamond testers. 

The setting of your jewelry can also offer some clues to whether you have a real or fake diamond. Real diamonds are often set in precious metals like gold rings, while fake diamonds are often found in more inexpensive settings.  

Finding Real Diamond Jewelry 

While these tests and techniques can help you get a better idea of whether you have a real diamond, the best way to tell if a diamond is real is to check with a jeweler. Every diamond is different, and some of these tests for how to tell if a diamond is real may not apply to certain diamond shapes, colors, cuts or clarity ratings.

You can browse our full selection of diamond earrings, women’s and men’s engagement rings, wedding rings and jewelry styles to see our wide array of diamond types available.

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