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.

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How To Tell If a Diamond Is Real: Cubic Zirconia vs Diamond (1)

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.

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How To Tell If a Diamond Is Real: Cubic Zirconia vs Diamond (2)

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.

How To Tell If a Diamond Is Real: Cubic Zirconia vs Diamond (3)

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.

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

FAQs

How To Tell If a Diamond Is Real: Cubic Zirconia vs Diamond? ›

If you visit any jewellery shop and find it difficult to differentiate between these stones, you should observe them in the brightest light. You will see that the diamond has white or silvery sparkles only. However, cubic zirconia will give out colourful sparkles such as red, yellow or blue.

How can you tell a cubic zirconia from a real diamond? ›

If you want to tell the difference between cubic zirconia and a diamond, look for a lower price tag, cheaper jewelry settings, and a more brilliant shine to indicate cubic zirconia. Or, use a microscope and look for hard edges, more spots or lines, and fewer scratches to indicate that you have a real diamond.

What is the easiest way to tell if a diamond is real? ›

If you have a loose diamond to test, fill a regular glass about ¾ of the way full with water. Gently drop the diamond into the glass. If the diamond sinks to the bottom, it's real. If it floats at the surface or just underneath, it's likely a fake.

Will cubic zirconia pass diamond test? ›

No. Cubic Zirconia (or CZ) does not have high enough thermal conductivity to pass. So, when you test a CZ with a diamond tester, it will not show as diamond. In fact, distinguishing CZ from diamond is one of the most important uses of thermal conductivity pen testers.

Are cubic zirconia diamonds worth anything? ›

Cubic zirconia is very inexpensive, since it's synthetic and mass-produced. A cut and polished one carat cubic zirconia stone will cost $20 and a similar two carat stone will cost about $30.

How to tell a real diamond ring by eye? ›

If you see a circular reflection inside the gemstone, the stone is fake. If you cannot see the dot or a reflection in the stone, then the diamond is real. Because a true diamond has powerful refractive qualities, light will bounce in different directions instead of a straight line.

How to tell if a diamond is real with a mirror? ›

This involves taking the diamond and attempting to scratch a mirror. If it leaves a mark on the mirror, it's a real diamond. However, the quality of false stones like cubic zirconia and moissanite has increased, and many can pass this test due to their durability.

Can the average person tell the difference between cubic zirconia and diamond? ›

You will see that the diamond has white or silvery sparkles only. However, cubic zirconia will give out colourful sparkles such as red, yellow or blue. Another important differentiating feature between these two stones is that a diamond possesses sharp facets, whereas a zirconium does not have sharp facets.

Can you test a diamond with your phone? ›

Can you test a diamond with your phone? You can use your phone's flashlight, or any flashlight, to test if a diamond is real. Simply shine the light on your diamond and look at how the light is dispersed by the stone. A real diamond will brilliantly show flashes of intense light and sometimes rainbows as well.

How to tell if a diamond ring is real with a flashlight? ›

If so, how to tell if a diamond is real with a flashlight? The real diamond will shine and glimmer when a flashlight is shone on it, while a fake diamond will not reflect light in the same way. The shine and glimmer of a real diamond are caused by the reflection of light from the surface of a perfectly cut diamond.

Do lab diamonds pass a diamond tester? ›

Yes, lab-created diamonds will test as real diamonds. Their identical composition and characteristics to natural diamonds mean they pass standard diamond tests with the same results.

What is the light test for raw diamonds? ›

Under shortwave ultraviolet light, 30% of diamonds glow blue. It will occur once you place a diamond under ultraviolet light. However, some will shine and generate different colours, such as yellow, red, or orange, making this procedure not 100% accurate.

How to make cubic zirconia look real? ›

Use a Jewelry Polishing Cloth

Most CZ jewelry pieces are often set in sterling silver or gold-plated metal. If you have one of these pieces, just use a jewelry polishing cloth to rub your CZ jewelry piece in a back and forth motion to restore your jewelry's shine and beauty.

How to tell a real diamond from cubic zirconia? ›

In cut stones, cubic zirconia tends to have dull, rounded edges, while diamonds' facets stay sharp. Diamonds rarely show polish marks, but if they do, they will be in different directions on different facets. On the other hand, cubic zirconia will show polishing marks in the same direction on adjoining facets.

What is the downside of cubic zirconia? ›

Cons: Durability. Despite its hardness, cubic zirconia's durability does not compare to diamonds. If worn every day, cubic zirconia will only last a few years.

Are Pandora rings cubic zirconia? ›

At Pandora, we use a rainbow of colored cubic zirconia stones, from icy blues to fiery reds and soft pinks.

Is cubic zirconia considered fake? ›

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.

How do I know if I have cubic zirconia or moissanite? ›

Moissanite has a higher hardness, more fire, and slightly more color variation, while cubic zirconia is typically colorless with less fire and a slightly lower hardness score. Both gemstones boast excellent clarity and a dazzling brilliance.

What does a real diamond look like in sunlight? ›

9. How to Tell if a Diamond is Real using Sunlight. The way that diamonds reflect light is unique: the inside of a real diamond should sparkle gray and white while the outside should reflect a rainbow of colors onto other surfaces.

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