How to Tell a Fake Diamond From a Real Diamond

Updated February 16, 2017

If you are buying a diamond sight unseen, beware of fake stones. With simulated stones sold as real diamonds on websites and in jewellery stores, the ability to determine the authentic diamond from a fake stone is essential. While white sapphires and cubic zirconium have similar shine and sparkle, unscrupulous vendors may sell these clear white stones as genuine diamonds. By looking for clues that reveal diamond authenticity and asking questions, diamond purchasers can recognise real diamond jewellery instead of a fabulous fake.

Examine the setting. Authentic diamonds are never set in low-quality metals. Read the stamp located inside the setting for its carat weight of 14K or higher and the ring's metal type. Platinum rings have the letters "Plat" or "PT" stamped inside the rings. If you see a stamp with the letters "C.Z.," the stone is a cubic zirconium and not a real diamond.

Identify flaws and imperfections. Most diamonds will have imperfections and small inclusions in the stone. Visit your local jeweller and use his diamond loupe to assess the stone's quality. Rotate the diamond at different angles between your two fingers to check for imperfections. A fake diamond--a lab-grown diamond or cubic zirconium--will have no imperfections.

Check for shine and fire. It is impossible for fake or lab-created stones to replicate the refractive index found in a real diamond. According to the shopping experts at AOL, synthetic stones can rarely duplicate the natural sparkle of diamonds. As a result, a fake diamond will look dull in bright light.

Ask your jeweller for a grading report. An authentic diamond has a certificate administered by the American Gemological Society (AGS) or the Gemological Institute of America (GIA). These gemological laboratories are not diamond sellers and do not receive a portion of diamond sales. AGS and GIA can authenticate the true value of a real diamond. Diamonds certified by these laboratories have a laser inscription implanted within the stone. View this permanent inscription number with the loupe. An authentic diamond's inscription will match the certificate number.

View newsprint through the stone. Use this unscientific diamond testing method to view the letters of an article through a stone. Place your loose diamonds down on the newspaper with the tip of the stone pointing upwards. According to the experts at On Dressing Well, if you can read the letters and the numbers on the newsprint clearly, then the diamond is probably a fake.


Gather information on the average retail price of a diamond's carat, weight and size. Ask the jeweller about the source of the diamonds, to determine whether it is man-made or real. If a diamond has a low price and is completely flawless, it is probably a fake.

Things You'll Need

  • Jeweller's diamond loupe
  • Diamond grading report
  • Newspaper
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About the Author

Mimi Abney is a lifestyle writer specializing in online content for women. Her work has appeared in and "Keepsake Magazine," among other publications. With over 15 years of writing and editing experience for the web and print, Abney is also a contributor to online health, beauty and fashion publications. She holds a Bachelor of Science in biology from Spelman College.