Diamonds are the hardest natural substance known to man, which makes them perfect for timeless pieces of jewelry such as engagement rings, earrings, and necklaces. Because of their incredible beauty and value, diamonds are often a pricey investment. Learning how to perform a few basic, at-home tests will help you to ensure that your diamond is a genuine stone and not a counterfeit cubic zirconia or glass stone.

Hold the stone up to the light and check the reflection colors. A color reflection test ensures that a diamond is reflecting or sparkling in shades of gray. Fake diamonds reflect a rainbow of colors. If your stone is sparkling in colors other than gray, it is not a genuine diamond.

Perform the scratch test. Because diamonds are the hardest substance known to man, they do not scratch or chip easily. If you can see visible scratches on the surface of the stone, it is most likely a fake diamond.

Perform the fog test. The fog test is done by holding the stone up to your mouth and breathing on it. Diamonds disperse heat quickly, so the fog from your breath should disappear right away. If the stone stays fogged for even a few seconds, it is not a real diamond.


  • Price is a good indication of authenticity. If you know your stone was inexpensive, it is probably not a genuine diamond.