How to Identify an Uncut Rough Diamond

Written by jesa lynn
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How to Identify an Uncut Rough Diamond
Unless you are well-trained, the best way to identify an uncut diamond is to take it to a jeweller. (crystal of garnet image by Alexander Maksimov from

Rough uncut diamonds are often confused with similar-looking materials such as cubic zirconia, moissanite and quartz. The easiest way to spot a real uncut rough diamond it to use a battery operated diamond tester. Testers can be purchased for about £58 and up and are very accurate in detecting genuine diamonds. The size of a tester makes it especially useful to prospectors, buyers, jewellers and pawn shop owners.

Skill level:

Things you need

  • Newspaper
  • Small mirror
  • Sandpaper (optional)

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  1. 1

    Let your stone sit at room temperature for 10 minutes without handling it.

  2. 2

    Pick it up and put it close to your mouth. Exhale on the stone to "fog it up."

  3. 3

    Look at the stone and see how long it takes for the fog to clear. If it is 3 to 5 seconds or less your diamond is possibly real.

  4. 4

    Place the stone on a newspaper if it is not completely cloudy. Try seeing the print through the stone. If you can read the print or see it clearly, the stone is likely a fake. This test can have mixed results if your stone is very cloudy.

  5. 5

    Scratch the surface of a small compact mirror. A real diamond should have no trouble scratching your mirror. You can also try rubbing the stone with sandpaper. A real diamond should not be scratched. However, doing scratch tests can ruin otherwise beautiful cubic zirconia jewellery and is not recommended.

  6. 6

    Take the stone to a jeweller if your tests prove inconclusive. A jeweller is your best and most accurate option and will tell you almost instantly if the stone is real or not. Often you can find a jeweller willing to check out your stone free of charge.

Tips and warnings

  • All of these tests can help you determine if your diamond is real but stone size and condition can cause conflicting or false results. A diamond tester should be used before purchasing a rough uncut diamond to avoid buying a fake.

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