How to Tell If Diamonds Are Real

Updated March 21, 2017

Manufacturers of low-quality and fake diamonds can easily fool the average person who has no knowledge of genuine diamond characteristics. Not knowing if a diamond is real or fake can be especially troublesome when giving or receiving a diamond to or from a loved one. If you have a diamond that you suspect may be fake, test it for authenticity.

Check for transparency. Slide a newspaper or other document with fine print under the diamond. Flip the diamond over and attempt to read the text through the diamond. If you can read the text, the diamond is fake. If you cannot read the text, it is most likely real. Low cut diamonds may have some transparency so perform a backup test to be certain.

Hold the diamond to your mouth and blow on it like you would fog a mirror. Check the diamond. If there is fog up to 4 seconds after blowing on it, the diamond is fake. This test is not appropriate for doublets, which contain a top diamond stone and a fake bottom.

Weigh the diamond using a gram scale. A fake diamond, such as the cubic zirconia, will weigh more than a real diamond of the same size. Expect the weight of a fake diamond to be about 55 per cent more than a real diamond.

Check a mounted diamond for authenticity. Inspect the diamond from the top to check for colourful reflections, which is an indication of a low-quality or fake diamond. Real diamonds reflect shades of grey. You will also not be able to see the bottom of a real diamond when looking down at it from the top.


Hire a professional diamond appraiser if you are uncertain about the authenticity of a diamond.


Be wary of crooks who try to sell unsuspecting buyers fake diamonds.

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About the Author

Charlie Gaston has written numerous instructional articles on topics ranging from business to communications and estate planning. Gaston holds a bachelor's degree in international business and a master's degree in communications. She is fluent in Spanish and has extensive travel experience.