How to Detect Fake Diamonds With UV Light

How to Detect Fake Diamonds With UV Light
Written By
Laura Heilman
Laura Heilman
Published: Feb 19, 2009
Updated: Jan 10, 2019
2 minute read

Whether you are buying a diamond new from a jeweler or used from a pawn shop, it is always wise to know the telltale signs of a fake diamond. While a professional will have the definitive opinion as to whether a diamond is authentic or not, there are ways to detect a fake. Fake diamonds differ from genuine diamonds in many ways. An ultraviolet light, also known as a black light, will reflect differently in most diamonds, thereby making it a useful tool in detecting fake diamonds. Buying a diamond is a large investment, one that may even be handed down through your family. You'll want to be sure that you're getting the real thing.

Hold the diamond in question under a long wave UV light (also called a black light). If the diamond reflects a blue fluorescence, it is most likely authentic.

Be aware that while the majority of diamonds on the market will have a blue glow under UV light, high quality diamonds will not. The UV light method should be performed along with other tests to detect a fake diamond.

Know that cubic zirconia will glow mustard yellow under a UV light. Glass will have no glow at all.

Familiarize yourself with the other methods of detecting fake diamonds, such as the reflection colors within the stone, the weight, the quality of the setting and the wear and tear on the stone itself.

Know that the final word on detecting a fake diamond is a professional appraisal. A certified and experienced gemologist will have the knowledge and skills needed to determine without a doubt that the diamond in question is authentic or a fake.

Warnings:

  • While there are many ways to tell the difference between a fake stone and a genuine diamond, these methods will not work to differentiate between naturally mined diamonds and those created in a lab. A detailed appraisal is recommended to distinguish among these types of gemstones.

Tips

Obtaining a certificate from the Gemological Institute of America (GIA) will ensure that the diamond has been graded for authenticity and quality. Don't be afraid to ask the jeweler about the diamond's authenticity. A reputable jeweler will appreciate the investment you are making and will want you to be satisfied.

Warnings

While there are many ways to tell the difference between a fake stone and a genuine diamond, these methods will not work to differentiate between naturally mined diamonds and those created in a lab. A detailed appraisal is recommended to distinguish among these types of gemstones.

Laura Heilman

Laura Heilman started writing professionally in 2006. Her work has been published on eHow and in online poetry journals such as 2RiverView and Steel Point Quarterly. She has an extensive background in library information services and holds…

Sponsored
Our Pastimes Logo

A destination for the avid collector and weekend hobbyist alike, Our Pastimes features articles and tips about your favorite cards and games, hobbies and more.

Property of TechnologyAdvice. © 2026 TechnologyAdvice. All Rights Reserved

Advertiser Disclosure: Some of the products that appear on this site are from companies from which TechnologyAdvice receives compensation. This compensation may impact how and where products appear on this site including, for example, the order in which they appear. TechnologyAdvice does not include all companies or all types of products available in the marketplace.