Lab-Grown Diamonds vs. Cubic Zirconia: What’s the Difference?

Hint: A lab-grown diamond is still a diamond.

lab grown ring

Courtesy of Misayo House

So, you adore the sparkle, luster, and overall look of diamond jewelry, but don’t want to pony up the cold, hard cash required—sometimes hundreds of thousands of dollars—to fully bling out. Enter: cubic zirconia.

This affordable stone was a staple of Millennial youth (remember those earring carousels at Claire’s?) and advances in its production keep churning out beautiful pieces that, to the untrained eye, can be tough to differentiate from real diamonds. "I love that people can feel good regardless of how much they spent," says jewelry designer Idunnu Tomori.

Meet the Expert

Idunnu Tomori is the founder of Misayo House Jewelry, a brand that creates classic and bridal jewelry styles using cubic zirconia stones. She is based in Atlanta. 

Still, as diamond creation evolves as well, there can be some confusion as to what is a synthetic, or simulated, diamond, and what qualifies as a real, true diamond. If you’re curious about the differences between lab-grown diamonds and cubic zirconia, you’ve come to the right place. Read on to uncover how they vary in the most important ways, including cost, durability, and sparkle.

What Is a Lab-Grown Diamond? 

A lab-grown diamond is just that: a diamond grown in a lab. Its chemical makeup is the same as a natural diamond—they are both comprised of pure carbon. The most common process for creating a lab-grown diamond is called chemical vapor deposition, which places a small, slim slice of an already existing diamond (which can either be natural or lab-grown) in a vacuum. The vacuum mimics the intense pressure and heat needed to create a naturally-occurring diamond, and carbon molecules assimilate to the diamond "seed." A lab-grown diamond typically takes between a few weeks and a few months to come to size.

What Is Cubic Zirconia? 

Cubic zirconia (CZ) is the crystalline form of zirconium dioxide. Though a version of CZ can technically appear in nature in another stone, it is extremely rare, and all CZ on the market today is manmade. CZs are colorless and look like diamonds to the untrained eye, but they do not have the same chemical makeup as diamonds. (As mentioned above, diamonds are carbon, CZs are zirconium dioxide.)  For that reason, they are sometimes called "synthetic" or "simulated" diamonds when referenced in overlapping spheres.

Lab-Grown Diamonds vs. Cubic Zirconia 

Price 

Because lab-grown diamonds are not finite in amount, not subject to the same supply chains, and take less labor and energy to produce than traditional mining, they often cost considerably less—sometimes up to 50 percent less—than naturally occurring diamonds of a similar grade. 

Cubic zirconia stones are even less costly to produce, primarily because they don’t require recreating pre-volcanic conditions that only exist far beneath the Earth’s crust. As such, they often go for a small fraction of what diamonds of similar size and cut would fetch, and the price disparity only increases as the stones increase in size. Per Tomori, a one- or two-carat CZ ring will almost never run you over $100.

Durability 

Like natural diamonds, lab-grown diamonds are comprised of pure carbon. They are the hardest substance on earth—a 10 on the Mohs hardness scale—and thus extremely durable. You can knock one around, wear one through physically demanding activities, and there’s very little chance the stone will fracture unless a preexisting inclusion near the surface causes it to. (Knocking the diamond out of its setting, though, is another story.) 

CZs are still hard—typically an 8 to 8.5 on the Mohs scale. They can typically withstand the typical wear and tear of everyday life just fine, but, per Tomori, "you might see some scratches from knocking your hand around."

If durability is important to you, moissanite, another popular diamond alternative, is harder than CZ. It clocks in between 9.25 and 9.5 on the Mohs scale. 

Clarity

Lab-grown diamonds are grown, just as natural diamonds are, albeit over a much shorter period of time. Because of this, the opportunity for inclusions, or tiny imperfections that can cloud a stone’s transparency, still arises. These inclusions impact a diamond’s clarity grade, which can range from Flawless (F1) to Included (I3). Lab-grown diamonds and natural diamonds are graded on the same scale because they are both diamonds. 

Cubic zirconia stones are machine-made, so no such opportunity for natural imperfection exists. They will not possess inclusions.

Carat 

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, with the CZ being slightly smaller than the diamond.

Quality Grade

As cubic zirconia is not made up of the same material compound as diamond, it is not graded on the same scales as diamond. CZs are instead rated on an overall quality scale of A (1A) to AAAAA (5A), with AAAAA being the highest quality. These ratings are most frequently referenced during wholesale purchases of CZs, and are not likely to be displayed in the typical consumer purchase. Per Tomori, the sweet spot for quality and price is AAA, and that’s the one you’ll most often find on the market from reputable sellers.

Color 

Whether they’re mined or lab-grown, completely colorless (grade D) diamonds are extremely rare—and extremely expensive. Most couples instead look for diamonds that are near-colorless, or graded G through J. Even in this range, any yellow tint that the diamond may take on would not be noticeable to the naked, untrained eye. 

CZs, on the other hand, are entirely colorless. They won’t feature any hue unless it’s intentional.

Shopping Considerations 

In the wedding realm, cubic zirconia features most prominently in the glitzy pieces brides don beyond their engagement ring—statement chandelier earrings, royal wedding-inspired bridal tiaras, etc. If made with natural or lab-grown diamond, these pieces would be infinitely more expensive, and not everyone has infinite budgets to splurge on items they may only wear once. 

Tomori also sees many clients purchase CZ stand-ins of their engagement rings and fine jewelry to wear while traveling, or in instances where it may make a person feel more comfortable to have a ring on. "I had a bride who hadn’t even gotten married yet lose her engagement ring," Tomori says. "It’s hard to go around saying you’re engaged and planning a wedding without one on."

FAQ
  • What’s the best size for a cubic zirconia stone?

    "A one-carat or two-carat stone is going to look more natural," says Tomori. "A bigger stone won’t have a lot of clarity, and it will look obviously 'fake.' If we go up to three carats total, [the ring] will be a diamond with settings on the side."

  • Can the average person spot the difference between a lab-grown diamond and cubic zirconia?

    If you’re giving a passing glance to a smaller-sized, quality CZ, it will be difficult to tell the difference between the simulated diamond and the real one. A closer inspection directly under the light, however, may reveal more of an intense, rainbow-hued sparkle coming off a CZ stone, whereas a diamond will reflect more white light. 

Related Stories