How To Tell If a Diamond Is Real: Cubic Zirconia vs Diamond (2024)

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. However, there are a few tricks to use at home to help you tell.

Learn more about the characteristics of diamonds and how to tell the difference between common imitation stones, like cubic zirconia, and natural diamonds.

The Obvious Differences Between Genuine Diamonds and Cubic Zirconia

The simplest way to tell if a gem is cubic zirconia or a real diamond is to inspect the stone for wear and color. 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. A diamond's facet edges will usually look incredibly sharp and precise. If the stone looks abraded or worn down it is likely not a genuine diamond.

You should also 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.

These are the easiest ways to test whether a diamond is genuine or it’s cubic zirconia. There are more in-depth methods as well. We cover these comparisons in more detail below.

Simon G. accent stones are always genuine diamonds or colored gems. Shop our Designer Jewelry Showcase to find handcrafted diamond jewelry pieces.

What is Cubic Zirconia?

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. However, there are a few types of stones that are used as diamond simulants, and cubic zirconia is by far the most common and the most realistic.

In fact, Simon G. engagement rings feature cubic zirconia center stones. By using cubic zirconia, our customers have more control over the shape, style, and cost of their engagement ring. Some of our customers even decide to keep theCZ center stone until a later date, offering them greater budget flexibility.

An In-depth Comparison of CZ Stones and Diamonds

Below we provide a more detailed overview of the key differences between diamond and CZ stones. From appearance to cost, there are a number of ways to tell if a diamond is real or an imitation.

Stone Appearance: The D-Z Color Scale

While many people incorrectly think a diamond should have a clear appearance throughout, gemologists understand that a “white” diamond can still have a yellow, gray, or brown tint. This is the backbone of the D-Z color scale. For example, an M color white diamond would be slightly more yellow than a F color diamond.

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. However, inclusions can usually only be viewed under a microscope, so it’s hard to use them as an at-home method of testing a diamond's authenticity.

Composition: Hardness And Density

While these stones may look somewhat similar, their composition is very different. A diamond is the hardest stone known to man while a cubic zirconia has a much lower rating of hardness.

This is because diamonds are made of compressed carbon atoms, which lends to their brilliance and their remarkable hardness. Various hardness comparisons can be made to test whether a diamond is really a diamond, or if it’s actually CZ.

You can also test diamonds by checking the stone’s weight. A diamond and a cubic zirconia can be the same in actual size, but on a molecular level, zirconium dioxide is slightly denser than carbon. As a result, aCZ stone will weigh more than a diamond of the same exact size.

Price: Genuine Diamonds Cost More

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. Of course, the best way to avoid any pitfalls is to shop with a reputable jeweler.

For decades, Simon G. has crafted generational jewelry to be passed down and cherished in your family for many years to come. Using the highest quality precious metals and gemstones, Simon G. has created a legacy in transforming creative concepts into breathtaking pieces.

Shop our designer jewelry showcase to find the perfect piece for any occasion.