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Should I Choose Cubic Zirconia (CZ) or Diamond? – A Quick Guide

Cubic zirconia engagement ring close up on finger

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Cubic zirconia (CZ) is the most popular diamond simulant and at first glance, looks exactly like a diamond. To the untrained eye, it’s next to impossible to tell the two stones apart and even for experts, using specialist tools is sometimes the only way to distinguish the two.

So if a cubic zirconia is so similar to a diamond, why spend thousands on a diamond instead of getting a similar look at a fraction of the cost?

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Let’s take a look.

What is Cubic Zirconia?

Beautiful round shape cz engagement ring in yellow gold

A cubic zirconia in a solitaire setting.

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Cubic zirconia is a lab-created stone made of zirconium dioxide. It was discovered in nature in the 1930s and by the 1970s scientists were producing synthetic versions of the stone due to its close similarity to diamonds. It became an instant hit in the use of costume jewelry and as technology advanced, was used in fine jewelry as well.

What is a Diamond?

Round shape diamond engagement ring

Stunning diamond engagement ring.

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Diamonds need little introduction. They’re the most popular engagement ring stone and are known for their exceptional hardness and durability. Diamonds have a history that dates back thousands of years. They’ve been used in jewelry around the world and were valued as containing mystical properties in India. Diamonds are made of carbon and form over millions of years, being pressed and heated by natural forces deep within the earth. Today there are also lab-created diamonds which are becoming increasingly popular.

Cubic Zirconia and Diamonds – the Main Differences

Just because they look alike doesn’t mean they perform the same way. Here are the 9 main ways cubic zirconia differs from diamonds:

Not as durable

Diamonds are the hardest known material with a perfect 10 on the Mohs scale of hardness. They’re extremely durable and highly resistant to scratches and damage. Note that they aren’t the toughest gemstone and can be quite brittle. And in case you were wondering, the toughest gemstone is jade.

Cubic zirconia, on the other hand, ranks at 8 to 8.5 on the Mohs scale. This is a good hardness, similar to other gemstones popular for engagement rings like aquamarine and morganite. But it can’t hold up over time and will acquire scratches and damage if exposed.

Harder to maintain

Diamonds are easy to maintain and may only require warm soapy water and a cloth to keep them shiny. A cubic zirconia, however, may become cloudy over time and might need to be replaced if it loses its shine and sparkle. This depends on the quality of the cubic zirconia as all CZ stones aren’t made equal.

Perfect colorlessness

Diamonds range in color from D to Z grades, and you can even find them colored diamonds. If you’re going for a colorless look, the more colorless the stone, the higher the value and demand. CZ tend to be perfect in terms of color, often equivalent to a diamond’s D grade (the highest color grade). Because it’s made in a lab, manufacturers can control how the CZ will look. You can also find cubic zirconia in a range of colors like red, blue, green, yellow and black.

Much more fiery

Fire effect in cubic zirconia

Gregory Phillips, CC BY-SA 3.0,

Although cubic zirconia doesn’t have the sparkle that a diamond does, it has much more intense fire (also known as dispersion). Fire refers to how light is broken up giving off little rainbows of color when under lights. Cubic zirconia has a more intense flashes of color than diamonds, which is more pronounced in larger stones.

No inclusions  

Like color, cubic zirconia is almost always perfectly clear with no impurities or structural imperfections. Diamonds range in clarity from Flawless to Included, but even the most visually perfect diamond can contain microscopic inclusions. The better the clarity, the higher the price.

Low value

This is where CZ shines (no pun intended). It’s much more affordable than a diamond and the price of a cubic zirconia ring is often largely determined by the quality of the setting rather than that of the stone itself.

There are quality grades of CZ to choose from and the higher the quality, the longer the CZ will last you. Not every CZ stone is worth being set in jewelry and some just don’t hold up over time like others. Cubic zirconia has no second-hand value and if you do decide to resell it, you might get something back for the setting but probably nothing for the stone.

Diamond engagement ring

Diamonds are the most sought-after engagement ring stone.

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Diamonds have always been valued as a prestigious gemstone. It maintains some of its market value, although you shouldn’t look at diamonds as an investment. You can rarely resell a diamond at market value, unlike gold for example. While a perfect 1 carat diamond will cost you about $10,000 a similar looking cubic zirconia might only set you back $20.

Higher density

Because cubic zirconia is denser than a diamond, it’s much heavier too. This means that if the carat weight of the two stones are the same, the CZ will be a little smaller than a diamond because it’s heavier.

Lower thermal conductivity

Diamonds are extremely good at conducting heat because of the way the carbon atoms are bonded together. Cubic zirconia, on the other hand, works as a thermal insulator. What this means is that if you fog up a cubic zirconia with your breath, the stone will take longer to clear up than a diamond. 

More environmentally friendly

As more young couples become aware of the impact of diamond mining on the earth, they look for more sustainable options. Cubic zirconia is environmentally friendly in that it’s lab-created and has little impact on the environment. Diamonds cause great destruction on ecosystems and there are also concerns of blood diamonds and unethical labor practices in the diamond industry.

How to Quickly Tell a Cubic Zirconia from a Diamond

Here are 5 ways to distinguish cubic zirconia from diamonds:

  1. Shine a light on the stone and notice the rainbow colors that come from it. If these are intense, you know it’s a CZ. Diamond’s aren’t as fiery.
  2. Cubic zirconia is twice as heavy as a diamond so check its weight relative to its size.
  3. If a material over 8.5 Mohs can scratch it, it’s CZ and not a diamond
  4. Cubic zirconia is completely flawless with no inclusions at all. Diamonds will always have some flaws.
  5. If you breathe on a CZ it’ll stay foggy longer than a diamond.

Should I Buy Cubic Zirconia or Diamond?

three cubic zirconia engagement rings

This depends on your budget and your values. Choose a cubic zirconia ring if the following relate to you:

  1. You have a strict budget and you don’t want to splurge on an engagement ring. You’d rather spend that money on your wedding, on a deposit for a house or to travel the world.
  2. You want an environmentally friendly stone that hasn’t cost the earth.
  3. You don’t care what other people think or will say about your ‘fake’ engagement ring.
  4. You don’t think that replacing a cloudy CZ over time isn’t a big deal.
  5. You don’t want to risk losing an expensive diamond while wearing it. If you lose a piece of CZ jewelry, you can always have it recreated.  
  6. Many celebrities often wear CZ replica jewelry to keep the real things protected in a safe and no one can tell the difference. Why not me too?
  7. You don’t want to buy into the de Beers marketing campaign that diamonds are the only way to show you love someone, that they’re a girl’s best friend and that they’re forever. You know better than that.