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How to tell a real Diamond from a fake Diamond

We are often asked how you can tell a real diamond from a fake diamond. With so many fake diamonds in the market, and more recently, replica diamonds becoming more and more abundant and closer to real diamonds than ever before, it’s important to know the quick things you can do to check the provenance of a diamond, and ensure you are buying a real and authentic diamond.

Here are a few ways you can check without any special tools or machinery whether a diamond is real or fake.

Look at the diamond and setting through a loupe

A loupe is a magnifying glass that you can buy at any jewellery shop and will let you take a closer look at your diamond and it’s setting. Once you have a loupe, there are three key things to look for when assessing your diamond:

  1. Look for imperfections. Diamonds are natural and formed in the earth’s mantle over millions of years, and therefore will likely show some imperfections. A fake diamond is usually completely perfect.

  2. Examine the edges. A real diamond will have sharp edges, whilst a fake diamond is likely to have rounded edges.

  3. Look at the quality of the mount. Most diamonds are mounted in gold or set in platinum. If the mount is cheap, it is unlikely it would be used to hold a real diamond.

Use the line test

The line test involves placing the stone on a single black line drawn on paper. It’s a great way to tell a real diamond from a fake. The line appears much more visible through a fake diamond. Place a diamond over the black line and watch the line disappear. 

Use the fog test

Breathe hot air on your diamond the same way you would if you were fogging up a bathroom mirror. A fake diamond will fog up for a short period of time whereas a real diamond will not because it won’t retain the heat.

Hold it up to the light

The way that diamonds reflect light is unique: Inside the stone, the diamond will sparkle gray and white (known as “brilliance”) while outside of the gem, it will reflect rainbow colours onto other surfaces (this dispersed light is known as “fire”). A fake diamond will have rainbow colours that you can see inside the diamond.

Understand refraction

Diamonds are so sparkly because of the way they refract and bend light. Glass, quartz, and cubic zirconium may mimic a diamond’s brilliance, but they have much lower refractive indexes.

This means that if your stone isn’t in a setting, you can place it over a newspaper and the light will scatter inside the real diamond and prevent a black reflection. A fake diamond will let the black shine through, and you may even be able to read a word depending on the size of the fake stone.

If you’re still unsure whether your diamond is real or fake, speak to a certified gemologist. At Hatton Jewels we have over 100 years combined experience in diamond jewellery, and hold certificates from the GIA (the Gemological Institute of America), the most trusted source of gemology knowledge. Just book a free appointment today and one of our specialist team members will get back to you. 

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