Lab-Grown Diamonds vs. Cubic Zirconia: The Real Difference

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To make a long story short, let’s do a quick rundown of lab-grown diamonds vs. cubic zirconia:

  • Both are good alternatives to natural diamonds.
  • Lab-grown diamonds carry a luxury aspect, making them ideal for engagement rings and fine jewelry. CZ ring, on the other hand, is much cheaper and commonly used for casual jewelry.
  • CZs are considered very cheap yet look pretty identical to a diamond for an untrained eye, making it the ideal diamond simulant for casual daily use.
  • A 1.00 carat lab-grown diamond would cost anywhere from $500-$1,000, depending on the characteristics of the diamond. Cubic zirconia would cost $5-$30
  • Both are available in different colors and qualities. 
  • A jeweler can tell the difference between diamonds, lab-grown diamonds, and cubic zirconia. A lab-grown diamond will test as a real diamond, and CZ won’t.
  • Cubic zirconia is considered a synthetic diamond and is commonly used as a diamond stimulant. On the other hand, a lab-created diamond is considered a real diamond due to its pure carbon chemical composition.

Test yourself: A lab diamond or a CZ? click to find out...

Table of Contents

What Is a Lab-Grown Diamond?

A lab-grown diamond is a diamond that is created in a laboratory by artificially growing diamond crystals from carbon. They are also sometimes called lab-created diamonds or cultured diamonds. Lab-grown diamonds have the same chemical and physical properties as natural diamonds; the main difference is their origin.

These diamonds are created in a controlled environment, which means that the quality and characteristics of the diamonds can be more closely controlled. This also makes them less expensive than mined diamonds.

A 3.00 carat lab-grown diamond

What Is Cubic Zirconia?

It’s a common misconception to think cubic zirconia and lab diamonds are the same. They are not the same at all. One is made of zirconium oxide powder, and the other is made of pure carbon and shares the same chemical composition of a mind diamond.

CZ (Cubic zirconia) is the crystalline form of zirconium dioxide. It’s created by taking zircon sand and heating it to over 1000 ° C (1832 ° F) in a furnace. The result is a beautiful stone that shows a lot of sparkles, an untrained eye won’t know it’s not a diamond.

Like lab-grown diamonds, cubic zirconia is very popular as an alternative to mined diamonds but more for casual jewelry. Synthetic diamonds like CZ might look good enough for someone who’s never seen a diamond. Remember that CZ exhibits flashes in most cases, only these of low quality look dull and hazy. Yet when comparing diamond vs cubic zirconia side by side, it’s easy to see the difference in brilliance and sparkles.

Don’t forget that cubic zirconia isn’t considered a real diamond but a simulated diamond. It holds very little market value and has a lower refractive index. That said, a cubic zirconia ring can be ideal for daily wear and entering the jewelry world without breaking the bank.

Lab-Grown Diamonds vs. Cubic Zirconia

When it comes down to the difference between these two stones, there are some notable differences. Let’s get down to it;


To put things in perspective, we must compare lab-created diamonds and CZ with natural diamonds.

Depending on the quality of the lab-grown diamond, a 1.00 carat weight is usually sold for around mid-high three digits. That said, it’s 60-80% cheaper than an identical natural diamond. For a diamond, that’s very affordable.

But what about cubic zirconia? That’s a way different story. Unlike natural and lab diamonds, CZ doesn’t carry any luxurious aspect. Other than looking good in a casual jewelry piece, it doesn’t bring significant value. For that reason, you can find a 1.00 carat cubic zirconia for a few bucks, $15-$30 top.

Check moissanite if you are looking for a diamond alternative but don’t want to pay thousands of dollars.


Since lab-grown diamonds share the same physical and chemical characteristics as natural diamonds, they also share the same hardness level, 10 on the Mohs hardness scale. That means lab-grown diamonds, and diamonds in general, are the hardest mineral known to society.

diamond molecular structure

Cubic zirconia follows lab-grown diamonds in the Mohs hardness scale, rated as 8-8.5, which is relatively high compared to other gemstones. It’s not as hard and durable as diamonds, yet it brings good value for money.


When picked right with high light performance, a lab-grown diamond would show more brilliance, fire (blue and yellow reflections) and sparkles to the naked eye. In terms of colors, the variety is still limited. You can find fancy-color lab-grown diamonds in yellow, red, pink and blue.

“Colorless” CZ would look like a crystal to the naked eye but won’t show as much brilliance as a diamond. In terms of colors, the variety is much wider: You can find cubic zirconia in emerald green, black, violet, and much more.

Quality Grade

imilarly to a mined diamond, lab-grown diamonds are inspected and graded with the 4c’s: Carat, color, clarity and cut. For that reason, if you buy a lab-grown diamond, make sure to buy a graded one, by IGI or GIA.

GIA lab-grown diamond certification

CZs have a different grading system that starts with an “AAAAA” rating for the highest quality and A/AB for the lowest quality:


  • AAAA
  • AAA
  • AA
  • A
  • AB

A high-quality CZ will appear very clear to the naked eye, while a low-quality CZ will appear dull and cloudy.

Cubic zirconia vs. lab diamonds: which one passes a diamond test?

Since lab-grown diamonds share the same chemical and physical characteristics as natural diamonds, they will test as real. However, there is a way to distinguish between natural and lab diamonds, but it can be done only with special equipment available at a gemological lab.

We are moving to cubic zirconia. A CZ will never test as a real diamond due to the different thermal conductivity levels of a diamond.

Which is better cubic zirconia or lab-created diamonds?

If you are looking for a valuable gemstone for casual fine jewelry and an engagement ring, a lab diamond would be more suitable. When picked right, a lab-grown diamond would show much more brilliance, fire and sparkle, harder and more durable.

On the other hand, if you are looking for a diamond alternative with a wide variety of colors and a low price tag, cubic zirconia might be a better option for you.


Lab diamond and cubic zirconia are two popular diamond alternatives. Here we compare the pros and cons of each to help you decide which is right for you. Lab-grown diamonds are created in a laboratory by artificially growing diamond crystals from carbon. At the same time, cubic zirconia is a lab-created synthetic gemstone that is made to look like a diamond. Cubic zirconia is less expensive than lab-grown diamonds but has extra durability. Lab-grown diamonds are harder than cubic zirconia and share the same physical and chemical characteristics as natural diamonds, making them difficult to distinguish from mined diamonds.


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Author: Yaniv Hadar

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