How to spot a fake diamond

Simple tests using fog, water, heat and more
You can tell a real diamond from a fake using simple, decade-long expert tips.
By Lubna Hamdan
Thu 26 Jan 2017 11:38 AM

You can tell a real diamond from a fake using simple, decade-long expert tips. And while the following ‘tests’ can help you distinguish your stone, they’re not always fool proof. Do check with an expert if you’re unsure, but make sure your diamond is clear of oil or dirt before you try the following tips, too.

1. Try the fog test

This is probably the oldest test in the book. Blow on the stone the same way you would on a bathroom mirror to create fog. Because real diamonds do not preserve heat well, they will not get foggy, whereas fake diamonds will fog up for a short period of time, according to experts. Alternatively, you could heat the stone over a lighter for 30 seconds and immediately drop it in cold water. A fake stone will crack, while a real diamond will not be damaged.

2. Drop it in a glass of water

Another water-related test is even simpler than the latter. Real diamonds are dense and heavier than other stones. Drop a loose stone in a glass of water to check its authenticity. If it’s real, it will quickly sink to the bottom, whereas a fake stone will normally float or sink slowly.

3. Check its reflectivity

Real diamonds sparkle because they reflect light. In fact, they do so strongly that you can’t see through it them. So if you want to test your stone, place it over written text and check if you can see the text’s colour – or even read it – through the stone. If you can, chances are the stone is fake, because a real diamond will reflect the text’s colour and will not allow you to see through it.

4. Examine the way it sparkle

Many people believe diamonds are meant to sparkle like rainbows, but they actually have a white or grey sparkle inside, but reflect rainbow colours outside and onto other surfaces. A fake diamond, on the other, will have rainbow colours inside of it, according to experts.

5. Rub it against a mirror

This is also one of the best known tests on how to spot a fake diamond, though it is not fool proof. Try rubbing your stone against a mirror. If the diamond is real, it will leave a mark on the surface (they are one of the world’s hardest stones after all) but will not be damaged itself, while most fake stones will not. However, some fake stones can sometimes scratch surfaces, too, so do pair this with other tests.

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