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If you’re in the market for a diamond, it’s important to know how to tell the difference between a real diamond and a cubic zirconia (CZ). While both can be visually similar, there are some key differences that can help you determine which is which. In this blog post, we’ll go over the main differences between diamonds and CZs so you can make an informed decision when shopping for jewelry.

What is a cubic zirconia?

Cubic zirconia, also known as CZ, is a synthetic gemstone made of zirconium dioxide. It was first created in the 1970s as an alternative to diamonds, and it has become a popular choice for costume jewelry and engagement rings due to its affordability and durability. CZs are created in a lab and are not found in nature like diamonds.

How does a cubic zirconia compare to a diamond in appearance?

Cubic zirconias are known for their brilliance and clarity, which can make them difficult to distinguish from diamonds at first glance. However, there are a few key differences to look for when trying to tell the difference between the two.

  • Color: Diamonds are typically colorless, although they can sometimes have a slight yellow or brown tint. CZs, on the other hand, can have a slight yellow or grayish color.
  • Cut: Diamonds are cut with precise angles and facets to maximize their brilliance and sparkle. CZs, while also cut with angles and facets, may not have the same level of precision and may not sparkle as much as a diamond.
  • Size: Diamonds are rare and valuable, which means they are typically smaller in size than CZs. If you see a very large stone that is supposed to be a diamond, it is likely a CZ.

How does a cubic zirconia compare to a diamond in durability?

Diamonds are known for their hardness and durability, with a rating of 10 on the Mohs scale of mineral hardness. CZs have a hardness rating of 8-8.5, which means they are less durable than diamonds and can scratch or chip more easily.

How can you tell the difference between a diamond and a cubic zirconia?

There are a few methods you can use to determine whether a stone is a diamond or a CZ:

  • The fog test: Breath on the stone and see how it reacts. Diamonds do not fog up easily, while CZs will fog up quickly.
  • The scratch test: Diamonds are very hard and difficult to scratch, while CZs are more prone to scratching. You can use a piece of paper or a loupe to try and scratch the stone. If it scratches easily, it is likely a CZ.
  • The water test: Drop the stone into a glass of water. Diamonds are denser than CZs, so they will sink to the bottom of the glass while CZs will float.


Knowing how to tell the difference between a diamond and a cubic zirconia can save you from making an expensive mistake when shopping for jewelry. By understanding the key differences between the two stones and using the methods outlined above, you can confidently determine which is which. If you’re in the market for a diamond, be sure to do your research and shop with a reputable jeweler to find your perfect engagement ring at Solomon Brothers Jewelers.

If you’re ready to buy a diamond or have any questions about diamonds and CZs, contact Solomon Brothers Jewelers for more information.