Cubic Zirconia Vs. Diamond: How To Tell What Is Real

Cubic Zirconia vs. Diamond: How to Tell What's Real

From clarity and hardness to cost, there are ways to spot a real diamond from a fake such as cubic zirconia. Learn the most important differences here. 

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What is Cubic Zirconia? 

Cubic zirconia is a much less expensive man-made gem that appears quite like a diamond, but they are very different. Cubic zirconia is a manmade mineral 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. Synthetic diamonds are also made in labs, but they have the same carbon structure as diamonds- cubic zirconias do not. 

Is a Cubic Zirconia Real?

A cubic zirconia is a real cubic zirconia, but it is not a real diamond. There are a few types of stones that are used as diamond simulants, but cubic zirconia is by far the most common and the most realistic. 

How to tell if a Diamond is Real?

There are several ways to tell if a diamond is real. Ultimately the only way to know for sure is to take it to a jeweler or gemologist who will be able to test it with official equipment. There's a few tricks to use at home that can give you a good guess, though. Since diamonds are harder than almost any other substance, diamond will not scratch or wear down - in fact, they will scratch other surfaces. If you have a microscope or magnifying glass, look at the very edges of the facets of the stone- if it looks soft, abraded, or worn down it is likely not diamond. A diamond's facet edges will usually look incredibly sharp and precise. Look at the color of the light as it enters and escapes the surface of the stone. If you turn both a diamond and a CZ upside down, the bottom of a diamond will give off the entire rainbow of color reflections, whereas CZs usually have more exclusively orange and blue flashes. This is because cubic zirconias and diamonds have different refractive indexes. Diamonds also transfer heat differently- diamonds are actually pretty good at thermal transfer compared to other stones, and so they will warm up faster in your hand than cubic zirconia will since cubic zirconia is more insulating. 

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Differences Between Cubic Zirconia and Diamond


This is the first step to determine a cubic zirconia trying to pass itself off for a diamond. While the two stones may look similar to the untrained eye, there are some subtle differences you should know. While many people incorrectly think a diamond should have a clear appearance throughout, diamond fanatics understand that a 'white' diamond can still have a yellow, gray, or brown tint. This is what makes the D-Z color scale- a M color white diamond would be slightly yellower than a F color diamond, for example. Cubic zirconia is more likely to be completely colorless which is a tell-tale sign it isn’t a diamond. Another notable difference is that a diamond will have natural inclusions throughout the stone which is a sure sign it is real. These inclusions can usually only be seen under a microscope. 


While these stones may look somewhat similar, the composition is very different between them. When looking to tell the difference between diamonds and cubic zirconia, consider the hardness. A diamond is the hardest stone known to man while a cubic zirconia has a much lower rating of hardness. Diamonds are made of carbon which lends to their brilliance and hardness. You can also test it out by checking the weight. A diamond and a cubic zirconia can be the same in actual size, but cubic zirconias are slightly denser and will  weigh more.


The final red flag that something isn’t right is the price. While diamonds come in varying prices due to the size or other factors determining the quality of a jewel, they will almost always cost more than a cubic zirconia. If a piece of diamond jewelry seems too low for what you are getting, ask to see the certificates to ensure it is a real diamond and not a fake stone or synthetic being passed as the real thing. While the biggest difference between diamonds and cubic zirconia is often the price, you should use your common sense. For example, a small diamond may cost less than a large cubic zirconia stone. Of course, the biggest way to avoid any pitfalls is to shop with a reputable dealer. When you build a relationship with a jeweler that has a strong reputation, you can feel more confident about the diamonds you are adding to your collection.

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