July 11, 2018 3 min read

tell real diamond from fake

How to tell if a diamond is real? You may have just received an heirloom you’re curious about, or one of the diamonds you’ve received seems a bit fishy. Of course, consulting an expert is best, but if you want to satiate your curiosity quickly and without leaving your home, here are a couple of tests you can to tell a real diamond from a fake one:

The Water Test

One of the simplest tests you can do to see if you have a real diamond on your hands is the water test. Fill up ¾ of a glass of water (it doesn’t matter which water you use) and gently drop the diamond into the glass.

Because a real diamond has high density, it will sink in the water. If, however, it floats either underneath or at the surface, its density is not at the right level for a diamond, and you, unfortunately, have a fake on your hands.

The Fog Test

For this test, all you need is your breath! Hold the diamond (it doesn’t have to be loose!) close to your mouth and breathe onto it, like you would if you wanted to fog up a mirror. A light fog should appear on the surface of the stone.

Since diamonds conduct heat effectively, the fog should disperse fairly quickly. If it takes several seconds for the fog to disappear completely, the diamond is likely fake.

fog test for smoking

The Newspapers or the Dots Test

One of the most important qualities of a diamondis its ability to reflect light – that’s that brilliance we’re all enchanted by! If you suspect your diamond doesn’t have a gleam it should have, you can check it with these simple tests.

Gently place your diamond, flat side down, on a piece of newspaper that has a lot of lettering. The light that falls on the stone should be bright, and make sure not a single shadow falls on the stone. Look through your diamond. If it’s real, you will not be able to read the letters. The light refracts in such a way, it should be impossible for you to see clearly through it.

The dots test is similar to the newspaper test. Draw a small dot on a piece of white paper. Then, put that paper on a flat surface. Place your gemstone on the dot, flat side down. Look down on the paper through the pointed end of the diamond. If you cannot see the dot, your gemstone is real.

Black Light

In case you have a UV light lying around, you can use it to check if your diamond is the real deal. First, turn off the light and place the diamond in front of the UV light beam. Most diamonds react with a UV lightand will emit a bluish glow. If you see a glow tinted in any other color, or no glow at all, the diamond may be fake.

The UV test is not definitive, so don’t lose hope just yet! Some real diamonds will not emit any kind of glow, and if you’re still unsure, it’s best to take it to a jeweler (we at Santayana can happily make that test for you!).

Heating the Stone

If you don’t mind potentially shattering your stone, you can test the diamond by heating it. To do this test, first, fill a drinking glass with cold water. Heat the diamond under a flame (a lighter will do) for about 40 seconds, then drop it into the chilly water. If the stone shatters, it’s not a diamond.

Remember that all of these at home tests are good if you want to satiate your curiosity, but for a more definitive answer, you’ll want an expert.

Do you have an heirloom stone you want to test safely? Bring it over to one of our stores, and we’ll help you!

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