Everything Diamonds, How to buy a diamond

How to Tell if a Diamond Is Real

by Haley Anhut
Posted July 29, 2020

Last updated on November 4, 2020

All diamonds are “real” or genuine; otherwise, they are simulated diamonds or imitations. This question hinges on what a diamond is.  Diamonds are a crystallized form of pure or nearly pure carbon. They are the hardest substance on earth. According to the Federal Trade Commission, whether they come from the earth or are created in a lab both are “real” or “genuine” diamonds composed of carbon in a crystallized form. All diamonds have a specific refractive index and no other material can duplicate it. They have unique chemical and optical properties unmatched in any other material.

Anything else is some form of imitation diamond.  It may generally mimic the appearance of a diamond but will be made from something else.  It will be less hard and have a different refractive index (a measurement of the light being refracted to the eye) than diamond. They may be made of a variety of other minerals like Moissanite, white sapphire, cubic zirconia, or even glass.  In keeping with FTC guidelines mined diamonds need only be called “diamonds” while “lab-grown diamonds” must be identified as such. It is actually illegal to call anything else a diamond per the FTC.

However, over the years, many companies have produced jewelry that not only imitates the look of diamonds but also uses confusing names that look or sound like diamonds such as Diamond Hybrid from MiaDonna, Diamond Essence from Nexus Diamond, Diamonique,  the Nexus Diamond,  and others.  None of these is an actual diamond. They are all just attempts to simulate the look of a diamond.

You may have also heard the word “synthetic” used to describe some diamonds or other gems.  Do not confuse “synthetic” with “simulated”.  A synthetic gem of any variety has the exact same chemical and optical properties as one found in nature. Simulated diamonds or other gems may be made of anything and are in no manner the same as the gem they are made to look like. Most have little to no value in the marketplace.  Some go so far as to have some carbon in the mix of materials. However, no matter the name their manufacturer may give them, they are not diamonds.

So, how do you know whether a “diamond” is real? 

At first glance, many imitations may fool a consumer but any trained jeweler, and with sufficient knowledge, most consumers can tell a genuine diamond from an imitation. Some can be identified by looking under magnification or by testing with a specially designed instrument.  If in doubt, be sure that the name and certification specifically state that it is a genuine diamond with no qualifying brand.  Both lab-grown and mined diamonds will test as genuine diamonds because they both are. Highly specialized equipment is needed to tell whether a diamond is lab-grown or mined but an imitation is much easier to spot.

Be wary of any “diamond’ of significant size that is not set in white or yellow gold or platinum.  It would be a very rare instance to have a 1/2 carat or larger diamond set in sterling silver.

If any doubt exists in your mind, make sure the diamond comes with a certificate from a recognized gem laboratory such as IGI or GIA.  All loose diamonds and engagement rings from Clean Origin are accompanied by a certificate from IGI and the identifying certificate number is laser engraved on the girdle for positive identification. 

An at-home test to authenticate a diamond

If you should find it necessary to test a stone that you have as to whether or not it is a diamond, the only somewhat reliable way is to invest in a diamond tester. They are available through some online retailers and while nominally priced, their accuracy is not infallible depending on the material being tested. If in doubt about the authenticity of a stone seek professional guidance.


How can you tell if a diamond is real or cubic zirconia or moissanite?

Both cubic zirconia and moissanite have different refractive indexes than diamonds. These and other diamond simulants also have different densities and other characteristics.  However, these are not things that most people can detect easily at home. Seek advice from a professional.

Can you see a difference between mined and lab-grown diamonds?

No. Both are diamonds and come in the same degrees of clarity, color, and cut.  Even a jeweler cannot tell the difference by sight.  Only the use of very specific laboratory equipment can reveal the origin.  Gem labs like GIA or IGI would have such equipment.  Your local jeweler most likely will not.

Can I determine if a diamond is real with a scratch test?

This is one of those questions where then answer is you can but you should not.  While diamonds are the hardest mineral on earth, they can also have their polish damaged or the diamond itself may chip if struck at just the right angle.  This test is also not entirely accurate as a diamond can scratch the glass but so will some other materials.   Once again, if in doubt, seek professional assistance.

Should my diamond glow under a black light?

This would only be true if the diamond has a relatively high degree of fluorescence.

Should my diamond float in water?

No. Assuming you are speaking about a loose stone, the diamond will sink.  However, this is not a valid test of whether a stone is or is not a diamond as other material will also sink but some imitation diamonds may float.  Therefore, if it floats, it is not a diamond. If it doesn’t, it may be a diamond.