Lab Grown Diamond vs Cubic Zirconia: Key Differences Explained

When choosing a sparkling stone for jewellery, you may come across both lab grown diamonds and cubic zirconia (CZ). While they can look similar at first glance, they are very different materials.

The key difference is simple: a lab grown diamond has essentially the same chemical composition and physical properties as a mined diamond, while cubic zirconia is a diamond simulant made from a different material.

So, which is better for your jewellery? Let's compare their composition, appearance, durability, price and suitability for everyday wear.

What Is a Lab Grown Diamond?

A lab grown diamond is created in a controlled laboratory environment using advanced technology that replicates the conditions in which diamonds form naturally. The two primary methods are Chemical Vapour Deposition (CVD) and High Pressure High Temperature (HPHT).

The result is a diamond with the same fundamental chemical, physical and optical properties as a natural diamond. The difference lies in how and where it was formed.

Like natural diamonds, lab grown diamonds are assessed according to the traditional 4Cs: cut, colour, clarity and carat, and can be independently graded and certified by recognised gemological laboratories.

See how a lab grown diamond is presented in fine jewellery with LOHR’s Dean Round Brilliant Four Claw Lab-Grown Diamond Band Engagement Ring.

Learn more about the process and characteristics in LOHR's guide to what a lab grown diamond is.

What Is Cubic Zirconia?

Cubic zirconia, often called CZ, is a synthetic gemstone made from zirconium dioxide.

It is specifically designed to resemble diamond and is popular because it provides a bright, sparkling appearance at a much lower price.

However, CZ is a diamond simulant, not a diamond. Its chemical composition, crystal structure and physical properties are different from those of diamond.

This means that although both stones can be lab-created, lab-created does not mean lab grown diamond.

Lab Grown Diamond vs Cubic Zirconia: Key Differences

Composition

The most important difference between lab grown diamond vs cubic zirconia is what they are made of.

A lab grown diamond consists of carbon atoms arranged in the crystal structure of diamond. CZ is made from zirconium dioxide.

This difference is responsible for their different hardness, optical properties and durability.

So, if you're wondering "Is cubic zirconia a real diamond?", the answer is no. It is a separate gemstone created to imitate diamond.

Appearance and Sparkle

Both stones can offer plenty of sparkle, but they don't interact with light in exactly the same way.

A well-cut lab grown diamond produces the characteristic combination of brilliance, fire and scintillation associated with diamond.

Cubic zirconia can also look extremely bright, especially when new. However, it has different optical properties and can produce more noticeable flashes of colour than diamond.

For someone who wants the appearance and light performance of a genuine diamond, a lab grown diamond is the closer choice because it is a diamond rather than a simulant.

You can see how different diamond cuts create distinct looks in LOHR’s Nassau oval cut and Varenne emerald cut designs.

Durability

Durability is particularly important for jewellery worn every day, such as engagement rings and wedding bands.

Diamond has a Mohs hardness of 10, while cubic zirconia has a hardness of approximately 8–8.5.

This makes lab grown diamond more resistant to scratching and better suited to long-term everyday wear.

Lab grown diamonds offer:

• Excellent scratch resistance

• Long-lasting brilliance

• High durability for everyday jewellery

• Suitability for engagement and wedding rings

CZ is still durable enough for many jewellery pieces, but it can show scratches and surface wear more easily over time.

Price

Price is one of the biggest differences between cubic zirconia vs lab grown diamond.

CZ is considerably less expensive because it is an affordable synthetic gemstone. It allows you to achieve a diamond-like appearance without spending as much.

Lab grown diamonds are more expensive than CZ because they are genuine diamonds. However, they can be a more accessible alternative to comparable natural diamonds.

If you're interested in how lab grown and natural diamonds compare, see LOHR's guide to lab grown vs natural diamonds.

Everyday Wear

Think about how you plan to use the jewellery before choosing between the two.

Lab grown diamond is a good choice for:

• Engagement rings

• Wedding rings

• Everyday rings

• Fine jewellery you want to keep for years

Cubic zirconia can work well for:

• Fashion jewellery

• Statement pieces

• Occasional wear

• Affordable jewellery

• Travel pieces

If you're choosing an engagement ring that will be worn every day, the greater hardness of lab grown diamond can make it the more practical option.

Certification

Lab grown diamonds can be independently graded by recognised gemological laboratories. A grading report can provide information about characteristics such as carat weight, colour, clarity and cut.

Cubic zirconia does not receive a diamond grading report because it is not a diamond.

If you're purchasing a lab grown diamond, certification can give you additional information and confidence about the stone you're buying.

You can learn more about diamond grading in LOHR's guide to lab grown diamond certification.

Lab Grown Diamond vs CZ for an Engagement Ring

When choosing an engagement ring, the differences between these stones become especially important.

A lab grown diamond may be the better option if you want:

• A diamond, rather than a diamond simulant

• Exceptional durability

• Diamond brilliance and fire

• A stone suited to everyday wear

• An independently certified diamond

• More flexibility in your budget compared with a natural diamond

Cubic zirconia may be suitable if your priority is keeping the cost as low as possible and you are happy with a diamond simulant.

Priority is keeping the cost as low as possible, and you are happy with a diamond simulant.

For lab grown diamond options, explore LOHR's lab grown diamond engagement rings.

Which Is Better: Lab Grown Diamond or Cubic Zirconia?

There isn't one answer for every buyer.

• Choose a lab grown diamond if you want a diamond with the durability, optical properties and longevity suited to an engagement ring.

• Choose cubic zirconia if your priority is an affordable stone that offers a diamond-like appearance.

The decision ultimately comes down to your budget, lifestyle and what you want from your jewellery.

Final Thoughts

The difference between lab grown diamond vs cubic zirconia ultimately comes down to what each stone is made of and how it performs.

A lab grown diamond is a diamond, with the same chemical, physical and optical properties as a natural diamond. Cubic zirconia is a different material altogether, created to offer a diamond-like appearance.

Lab grown diamonds offer the brilliance, durability, and longevity associated with diamond, making them particularly well suited to engagement rings and everyday fine jewellery. Cubic zirconia, meanwhile, offers an accessible option for those looking for the appearance of a diamond at a lower price point.

Understanding that distinction makes choosing between the two much simpler.

FAQ

Is cubic zirconia a real diamond?

No. Cubic zirconia is a diamond simulant made from zirconium dioxide. Lab grown diamonds have the same chemical, physical and optical properties as natural diamonds.

Is a lab grown diamond better than CZ?

A lab grown diamond and cubic zirconia have different properties. Lab grown diamonds share the same chemical and physical properties as mined diamonds, while cubic zirconia is a diamond simulant made from zirconium dioxide.

Can you tell the difference between CZ and a lab grown diamond?

They can look similar, but their physical and optical properties differ. Gemological testing can distinguish between them.

Which lasts longer, CZ or lab grown diamond?

Lab grown diamond. Its hardness of 10 on the Mohs scale makes it significantly more resistant to scratching than CZ.

Is CZ suitable for an engagement ring?

It can be used for an engagement ring, particularly when budget is the main consideration. However, lab grown diamonds are generally more suitable for everyday, long-term wear.

Is cubic zirconia cheaper than lab grown diamond?

Yes. CZ is significantly less expensive because it is a different synthetic gemstone rather than a genuine diamond.