Cubic Zirconia Versus Diamond: How to Tell Which is Real

Wondering how to tell the difference between cubic zirconia and a diamond? Are you worried about being fooled by cubic zirconia? I was like you once and spent hours of research to learn the best ways to tell the difference between real and fake diamonds. So don’t worry, we’ve got you covered.

How to tell a real diamond from an imitation cubic zirconia? The difference in cost, as well as the color, clarity, sparkle, and hardness of the gemstone, is what helps us tell real diamonds apart from cubic zirconia. Diamond testers are the best way to tell the difference between a diamond and cubic zirconia.

In this post, we’ll go over everything you need to know about diamonds versus cubic zirconias so you can make your purchase decision with confidence!

What is a Cubic Zirconia?

Cubic zirconia, also known as CZ or an American diamond, is a lab-created gemstone that closely resembles diamonds.

Cubic zirconia is a much less expensive man-made gem. It is made of zirconium dioxide. CZs can appear to be very like diamonds, but they have very different mineral structures.

Cubic zirconias have been found in nature in small amounts, but the vast majority used in the jewelry are man-made in a lab.

So is a Cubic zirconia real?

Is a cubic zirconia real? No. A cubic zirconia is a type of fake diamond.

Cubic zirconias are lab-created gemstones, and they don’t have the same mineral structure as diamonds.

Cubic zirconias are not natural stones and cannot be found in nature. They’re manufactured for use in jewelry because of their low price point, durability, brilliance, and colorless or near-colorless appearance when compared with other gemstones like sapphires or rubies.

READ MORE >> How Cubic Zirconia (CZ) and Lab Diamonds are Different

10 Ways to tell if a Diamond is real.

How do you tell if a diamond is real? It’s actually very difficult.

There are several methods for testing authenticity at home before taking the diamond into an official jeweler or gemologist who will have equipment that can confirm its real-ness with certainty.

Does it look worn or scratched? Diamonds are harder than almost any other substance, so they won’t scratch or wear down. If you have a microscope or magnifying glass, look at the surfaces. If it looks worn down or scratched up it is probably not diamond.

Are the edges and points sharp? Look for the edges of a diamond’s facets and if they look worn or soft, it may not be a diamond. Diamonds are sharp and do not wear down like other gemstones, so if the surface appears softened, it is likely not diamond.

Can you scratch it? If you try to scratch a diamond and the scratches remain visible but if you rub against cubic zirconia, the scratches will vanish because of their low hardness level as compared to Diamonds which is one out of ten on Moh’s scale.

Can you see through it? Diamonds are clear and will not show any light coming through. If it looks cloudy or the surface is white, then it’s probably a fake diamond.

Are there rainbow colors in the stone? It may be possible to find some color within diamonds if they have been cut poorly or cheaply but generally speaking, an authentic diamond will not have colors on its body.

Is there anything inside of cracks in the gemstone that does not belong there? For example, dirt particles can sometimes get stuck inside of natural stones like this more easily than other types because their surfaces actually appear rougher on close inspection.

Does it sparkle? The best way to tell if a diamond is real or fake, is to see how it responds under the light. Diamonds sparkle more brightly because they refract light better whereas fake gems might appear dull even when placed in direct sunlight.

The sparkle you see in a diamond is because of the way light interacts with its surface. Fake diamonds won’t sparkle in the same way that real ones do, which is why it’s fairly easy to tell the difference.

Does it get warm fast? Diamonds are good at transferring heat. Diamonds transfer heat better than other stones so they warm up faster in your hand.

Does it float? Try boiling a pot of water and dropping your gem in. Diamonds will sink to the bottom. Cubic zirconias or other artificial stones will float on top. Similarly, you can put ice cubes on them and see which one melts faster. The cube touching the diamond should melt first.

Buy a diamond tester. If you’re still not sure, the easiest way is to buy a “diamond tester.” They are inexpensive and can usually be found in jewelry stores or online. Find out more about diamond testers and our review of best diamond testers.

The 7 physical differences between a Diamond and Cubic Zirconia.

There are 7 ways to tell the difference between Diamonds and Cubic zirconia.


Cubic zirconia stones are almost always clear or near-clear because they’re made of glass.

Diamonds have inclusions and other imperfections that make them more interesting to look at. The more perfect a diamond is from the inside out, the higher its value as they usually have fewer imperfections or “inclusions.”

This doesn’t mean that diamonds with many inclusions can’t be valuable to some people just like any other piece of art because it’s beautiful despite its flaws.


Cubic zirconia stones are all the same shape and size.

Diamonds come in lots of different shapes, sizes, cuts, colors, and clarity grades.


Many people don’t know that a diamond can be white even if it does not look clear. Diamond experts know that diamonds can have different colors within them. For example, a D-Z color grade scale is different colors within the white diamond. An M color would be slightly yellower than an F color.

Cubic zirconia is more likely to be completely colorless which means it isn’t a diamond.


Cubic zirconias also have more sparkle than diamonds because their surface tends to be very finely textured while diamonds tend towards smoother surfaces that catch light better for a brilliant shine.

Diamonds also contain nitrogen which contributes to their fire or luster making them sparkle! Cubic zirconia has no such properties.


When you are looking at stones, you can tell the difference by feeling them. Diamonds have a hardness that is much higher than cubic zirconia and they also weight more as well.

Diamonds are composed of carbon atoms in a tetrahedral crystal lattice. One of the reasons that diamonds are so brilliant and hard is because they are made up mostly of carbon.

Cubic zirconias are made up of silicon and oxygen that is arranged like cubes to create the diamond look.

For the best test of authenticity, you can weigh them to see which weighs more. Diamonds are denser than cubic zirconias and will always have a heavier weight.


A Cubic Zirconia is not certified by the GIA.

A diamond is certified by the GIA, an independent and respected gemstone certification company. Diamonds can come from many sources which makes them more difficult to pinpoint their origin than other gems like rubies. The best way to tell if your diamonds are real would be through certification companies such as the GIA who certify diamonds based on four C’s: cut, carat weight, clarity and color.

If you are looking at stones that do not carry this stamp of authenticity, then they are most likely cubic zirconia imitations or some other fake diamond.


Due to their scarcity, diamonds are much more expensive than cubic zirconias.

Cubic Zirconia is about one-fourth the cost of a diamond!

The difference in prices can be attributed to the rarity and value of each stone. Diamonds have many qualities that make them valuable beyond just being rare which allows for high demand and pricing on them. Cubic zirconia lacks those qualities so it costs less because they are not as desired or needed by consumers.

Cubic Zirconia vs Diamond Wrap Up

The key to avoiding a diamond scam is understanding the differences between cubic zirconia and diamonds.

Cubic Zirconia (CZ) has very similar properties of natural diamonds, but are much cheaper than their gemstone counterparts.

Most people can’t tell the difference just by looking at them! If someone tries to sell you a diamond ring with no paperwork, they might be trying to trick you. A real diamond will have paperwork.

If you’re not sure how to spot fakes, ask for documentation from your jeweler before buying any jewelry pieces that seem too good to be true!

Don’t get ripped off – know what’s real and what’s not when it comes down to shopping for a diamond.

Carl A. Jones, GIA GG

Carl A. Jones is a GIA Graduate Gemologist with over 20 years of experience in the diamond industry. He is an independent jewelry appraiser. He specializes in determining the value of diamonds and advising consumers on how to buy quality diamond jewelry.

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