Lab Diamonds vs Cubic Zirconia

If you’re shopping for an engagement ring, you’ve likely seen alternatives to earth-mined diamonds, such as lab grown diamonds and cubic zirconia. Both are ethically sourced, environmentally friendly, durable, and affordable. Keep reading to learn more about the similarities and differences of these sparkling gemstones.

What Are Lab Diamonds?

Lab grown diamonds provide consumers with a “real” diamond that shares the same chemical composition, optical properties and physical features as natural diamonds. Lab diamonds are made of carbon like natural diamonds.

The process to create a lab grown diamond is similar to the process to create natural diamonds–the only difference is one occurs within the earth’s crust and the other occurs in a laboratory. To create a lab grown diamond, the manufacturing process replicates conditions that create a natural diamond creation–extreme temperatures and pressures that turn carbon into a diamond.

Like diamonds, lab grown diamonds are evaluated using the same color, cut, carat and clarity scales that natural diamonds are, so review this information while shopping for stones. Grading determines the diamond’s quality.

What is Cubic Zirconia?

Like lab diamonds, cubic zirconia is also a synthetically created stone, but its crystal structure and chemical composition is completely different. While lab-grown diamonds are made of carbon, cubic zirconia is the cubic crystalline form of zirconium dioxide. It’s not a diamond, but is an affordable diamond alternative.

Cubic zirconia is made by melting zirconium oxide powder with stabilizers like magnesium and calcium at 4,982ºF. After being removed from hours of heat, crystals form and stabilize. The crystals are then cut and polished. Every lab has its own specific methods for making cubic zirconia.

Cubic zirconia are graded differently. They’re colorless and internally flawless, so the cut and carat are what you need to evaluate. Cubic zirconia is sometimes graded into the following categories: A, AAA and AAAAA. Grade A are of the lowest quality and are easily damaged, chipped and tarnished, 3A are mid-range stones and 5A are of the highest quality with little difference in appearance to diamonds. Additionally, 5A CZa are marketed as being hand cut and polished, so they’re the best versions of CZ..

Cubic zirconia is slightly denser than diamond, which makes it heavier. A cubic zirconia and a lab-grown diamond of the same carat weight will not be the physical same size–the diamond will be slightly bigger.

Lab Diamonds vs Cubic Zirconia

A helpful way to analyze lab diamonds and cubic zirconia is to compare them

Grown Diamonds Cubic Zirconia
Chemical Composition Carbon ZrO2
Hardness 10 8.25
Dispersion 0.044 0.066
Reflective Index 2.42 2.2
Purity All production is Pure Carbon Contains Zero Carbon
Fossil Fuels Required Negligible Negligible
Water and Land Use Negligible Negligible

  • Availability: Both cubic zirconia and lab diamonds have high availability because they’re lab made and not earth mined.
  • Appearance: Lab diamonds and cubic zirconia look similar, but they have differences you can notice in terms of the sparkle, inclusion and cut. Cubic zirconia’s brilliance is different (more on that in a moment), and they have no inclusions. The CZ isn’t as hard, so the edges are more rounded than diamonds.
  • Sparkle: CZ has higher dispersion (0.058 – 0.066) than a diamond (0.044), so when it’s exposed to light, CZ exhibits flashes that are more colorful than those of lab grown diamonds. A lab created diamond reflects light in more complex ways, known as its brilliance, and gives the stone its coveted sparkle
  • Refraction: Cubic zirconia has a much lower refractive index (2.171 – 2.177) than a diamond (2.417 – 2.419). That means when cut and polished, CZ does not show true brilliance and fire because light passes through it much differently. This difference causes different types of brilliance from each stone.
  • Durability: Lab created diamonds have a hardness of 10 on the Mohs hardness scale while cubic zirconia has a hardness of 8-8.5.
  • Color:Like natural diamonds, lab grown diamonds vary in color. They’re graded according to the same standards as natural diamonds (D–Z, colorless to light yellow or brown). CZ is colorless and won’t have a hue unless it’s intentional.
  • Price: The lab conditions to produce cubic zirconia and lab grown diamonds vary, so the cost between the stones varies as well. CZ will be less expensive than lab created diamonds.

Should You Choose CZ or Lab Diamond?

Lab diamonds are optically, chemically and physically the same as earth-mined diamonds. They’re a popular choice for engagement rings because of their long list of benefits.

  • Durability: They remain the hardest material on earth—a 10 on the Mohs hardness scale—and are as difficult to chip as a natural diamond. Cubic zirconia isn’t as hard (8-8.5 on Mohs).
  • Quality: Lab-created diamonds sparkle like natural diamonds, and you can find stones that have higher-quality clarity with fewer inclusions without paying a lot. You can get a high-quality, bright, glittering lab-grown diamond in your budget.
  • Ethically sourced and conflict free: Unlike most natural diamonds, you can pinpoint the origin of lab grown diamonds.
  • Environmentally friendly: The environmental impact is reduced by purchasing lab created diamonds because mined diamonds have a huge impact upon environments, landscapes, and communities.
  • Cost: Lab grown diamonds cost significantly less than natural diamonds and you can get more for your money
  • Availability: You have plenty of certified options for lab-made diamonds, and you can find cubic zirconia options.
  • Choices: Lab-grown diamonds are available in a wide range of cuts, such as pear, emerald, oval, and princess.

Some tips and factors for shopping for your jewelry:

Lab diamonds and cubic zirconia are both beautiful and make good alternatives for natural diamonds in jewelry. However, lab-created diamonds have many more benefits for all of the above reasons (durability, hardness, sparkle, certification, etc.)


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