How to Tell If a Diamond Is Real: Spotting Fake Diamonds

Angelica Frey | September 18, 2023

There are a lot of materials that are used to represent diamonds that aren’t real diamonds. Cubic Zirconia or CZ is probably the most well known, but there are other diamond simulants on the market like moissanite or even white sapphire and white topaz.

“Historically, fake gemstones were made out of paste or glass with a metallic backing to make them look like they sparkle,” says Grace Taylor, VRAI’s Senior Director of Sales and Customer Experience. “Basically anything that isn’t carbon is not actually a diamond, and could be considered fake.” Not all fakes, however, are made alike, and some are gemstones in their own regard.

Lab-created diamonds are not fake diamonds or diamond simulants. Lab-grown diamonds, like VRAI created diamonds, are made of carbon, which makes them real diamonds. The U.S. Government also validated lab grown diamonds as real diamonds. Learn to tell real diamonds and diamond simulants apart to make an informed purchase, whatever that will entail.

What Is a Real Diamond?

A real diamond is any gemstone that is almost entirely composed of the element of carbon, and whose atoms are arranged in a crystal structure. In that structure, each atom bonds the same way in all directions. It’s good to specify this because graphite is made of carbon too, but the atoms bond differently.

This definition applies both to mined diamonds, which originate around 100 miles below the Earth’s surface, and to lab-grown diamonds, where conditions of extreme heat and pressure are recreated in a controlled environment.

What Is a Fake Diamond?

Any gem that is not made of carbon and that is intentionally made to resemble a diamond can be considered a ‘fake’ diamond. The technical term is ‘diamond simulant,’ and they have a series of practical usages.

They are less expensive than diamonds, and when set in rings, charms, or pendants, they reproduce, to varying degrees, the sparkle of diamonds. These characteristics make them suitable for entry-level and on-trend jewelry.

What Are the Most Common Diamond Simulants?

The most common diamond simulants include, but are not limited to:

  • Glass
  • Cubic Zirconia
  • Topaz
  • White Sapphire
  • Moissanite (debated)

Are Lab Grown Diamonds Real Diamonds?

Lab grown diamonds are real diamonds. Man-made environments can recreate the extreme heat and pressure that took place in the Earth’s mantle millions of years ago. The result is a gem that is chemically and physically identical to mined diamonds. This means that lab-grown diamonds have the same properties as mined diamonds, and have varying degrees of color and clarity.

Lab grown diamonds are also graded with the same criteria as mined diamonds in terms of cut, carat, color, and clarity. The only difference between lab-grown diamonds and mined diamonds lies in the former’s lack of human and environmental toll.

How to Spot a Fake: The Main Telltale Signs

Methods to spot a simulant vary depending on what simulant you’re working with. Some diamond simulants have markedly different levels of hardness and weight, others have different scintillation patterns compared to carbon-made real diamonds.

Check the Scintillation

Depending on the diamond simulant, its scintillation, fire, and brightness can speak volumes of its true nature. Let’s take moissanite, a gem that, in the last decade, has gained enormous popularity because its brilliance and budget-friendly price point allowed for the creation of opulent, maximalist engagement rings and jewelry.

“Moissanite is easy to tell from diamond because moissanite has a lot more rainbow refraction than a diamond - many people describe moissanite as having a “disco ball effect” in strong light,” says Taylor. “To get more technical, moissanite is a double refractory material (as is sapphire) and diamond is a single refractory material, so the way light moves through these materials is totally different.” Cubic zirconia have a similar, rainbow-like refraction.

Sapphire and white topaz, by contrast, have a much more subdued scintillation and brilliance, and look more glass-like than diamonds.

Check the Weight

Diamonds and diamond simulants have different weights at the same size. This is called density or specific gravity. Diamonds have a specific gravity (SG) of 3.52. Diamonds are much heavier than moissanite (SG 3.1-3.2), but lighter than white sapphire (SG 4.0) and cubic zirconia (SG: 5.5-6.0). White topaz and diamonds have a similar density.

Mind the “Fog”

If you need to tell a diamond apart from a cheap simulant such as Cubic Zirconia, just breathe on it. “If you huff your breath on a diamond, the fog created will dissipate very quickly if the stone is a diamond because diamonds have low thermal conductivity,” says Taylor. “Cubic Zirconia will stay clouded with your breath for longer.”

Take Diamond Testers With a Grain of Salt

There are diamond testers that are able to identify real diamonds using heat conduction. “Diamond testers are easy to use improperly, however, so you want to take those readings with a grain of salt unless they’re performed by a professional on a completely clean stone,” warns Taylor.

How Does Moissanite Compare to Diamonds?

Moissanite is a (predominantly) lab-grown material that looks somewhat like a diamond as it is a clear stone, but it is silicon carbide rather than carbon. Original moissanite comes from a meteor and was discovered in 1893 at the enormous meteor crater in Arizona.

“It has a similar hardness on the Mohs scale (9.0 to 9.5 compared to a diamond’s 10) and is clear, and often chosen as an engagement ring stone for these properties,” says Taylor. “It isn’t a diamond at all, nor is it intended to be, since if you know what to look for you can easily tell them apart.”

How Does White Sapphire Compare to Diamonds?

White sapphire and topaz are often used in fine-jewelry lines that strive to balance quality and affordability. “Both white topaz and white sapphire are going to be far less brilliant than a real diamond; they won't have any of the rainbow refraction we call fire and so they are fairly easy to tell from a diamond,” explains Taylor. “They can have more of a glassy appearance as a result.”

In terms of hardness, white sapphire is a 9.0 on the Mohs scale. So, they need more care and can get chipped or scratched more easily than a diamond. However, sapphireshave a higher refractive index which gives them a sparkle that many find appealing.

How Does White Topaz Compare to Diamonds?

Topaz shares a few characteristics with sapphire, but it’s both less scintillating and less hard. Topaz is an 8 on the Mohs scale. On the other hand, topaz has a lower price point than sapphire, which makes it suitable for entry-level and everyday jewelry.

How Does Cubic Zirconia Compare to Diamonds?

Cubic Zirconia, also known as CZs, are colorless lab-grown gemstones that look similar to diamonds. They are made of zirconium dioxide, and they’re naturally colorless and without inclusions. Their scintillation is very different from the one displayed by diamonds. Diamonds cast a bright, white light and, to a lesser extent, rainbow-like fire. CZ only display rainbow-like flashes.

In all, learning how to tell if a diamond is real is a multi-step process that does not have a one-size-fits-all approach. However, it is a skill that can be mastered, at least at a beginner level.

What Is a VRAI Created Diamond?

A VRAI created diamond is a lab created diamond grown in a foundry Carbon Neutral certified as true zero-emissions. This means a VRAI created diamond was sustainably created with no human or environmental toll. This means you can trace their origin with 100% certainty. The rough diamond is then cut and polished by master craftspeople into over 30 shapes and any size making VRAI created diamonds a completely unique bespoke diamond experience.

Each carat of VRAI created diamond saves:


lbs (65kg) of carbon dioxide


ounces (57 kg) of air pollution


tons (227 tonnes) of earth

virtual appointment with diamond expert meeting with potential customers over a call on a computer
virtual appointment with diamond expert meeting with potential customers over a call on a computer

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Speak with our diamond experts and enjoy:

  • Personalized guidance to select your ring
  • In-depth diamond 4C education
  • Exclusive in-store fittings or virtual try-ons
  • Custom design options