Free Shipping
Secure Checkout
Always Certified
24 Hour Customer Service

Lab Created Diamonds vs CZ

Natural diamonds aren’t for everyone. If you love the sparkle of diamonds but want to wear something that is made, not mined, you might be considering alternatives for an engagement ring or special piece of jewelry. Whether your concerns are ethical, environmental or financial, you have more options to mined diamonds than ever before. For decades, the most available and affordable diamond imitation has been cubic zirconia, also known as CZ. But today you also have the option of lab-grown diamonds: real diamonds that are created by man.

What are the similarities and differences of CZ vs lab-grown diamond? Here’s what you need to know about how lab-grown diamonds compare to CZ.

Cubic zirconia is manufactured in large quantities so it is inexpensive.

What is CZ?

Since it was invented in the late 1970s, the most popular diamond simulant (a fancy word for imitation) has been cubic zirconia, popularly known as CZ. It’s not “CZ diamonds” as some people call it because CZ isn’t diamond at all.

Cubic zirconia is a synthetic zirconium oxide grown in the lab specifically as a diamond simulant. Why has it become so popular? It is white, bright, brilliant with a high refractive index, and quite affordable. How affordable? You can buy a one-carat CZ for about $10.

Zirconium doesn’t form cubic crystals naturally. To create CZ, it has to have a chemical stabilizer added to make it stable at room temperature. Usually crystals have either yttrium or calcium oxide added to keep them stable. That means CZ has a range of physical, chemical and optical properties. It also means that some CZ isn’t completely stable and will yellow and degrade over time.

CZ has a pretty good hardness of around 8.5 and is a pretty convincing diamond imitation. Jewelers use it in sample designs because it gives you an excellent idea of what the piece will look like when set with diamonds. It has less brilliance than diamond but slightly more fire.

Even if you aren't a gemologist, you can easily distinguish between diamond and CZ with an inexpensive testing pen that measures thermal conductivity.

CZ is a bit denser than diamond which causes some confusion. A one-carat CZ will be much smaller than a one-carat diamond. That’s why CZ is generally sold by size instead of by carat weight.

CZ is a great choice for fun fashion jewelry in brass or silver or travel jewelry that you won’t worry too much if you lose it. You can wear it for a few seasons and if the sparkle begins to dull, you can just replace it.

Unfortunately some retailers of cubic zirconia try to obscure the fact that they are selling CZ. They use language that suggests that their products are set with lab-grown diamonds not diamond imitations. This enables them to charge more than other sellers of cubic zirconia jewelry.

It can be confusing to consumers when sellers describe CZ as “a lab-created diamond simulant.” The FTC warned five sellers of branded CZ, including Diamond Nexus, MiaDonna and Agape, not to use language that “falsely implies that the jewelry has laboratory-created or mined diamonds.”

Lab grown diamond is identical to mined diamond

What is Lab-Grown Diamond?

Unlike CZ, lab-grown diamond is actually diamond. Lab grown diamonds are physically, chemically, and optically identical to mined diamonds.  The only difference is where they formed. Natural diamonds formed a billion years ago or more deep within the earth. Lab-grown diamonds are made by man using high-tech equipment.

Because lab-grown diamonds are identical to mined diamonds, advanced gemological equipment that looks at the crystal growth structure is required to tell them apart. You can’t tell by just looking at them, even with a loupe.

Lab grown diamonds are cut and polished just like mined diamonds so you can find them in the same shapes and cuts. Lab-grown diamonds in large sizes are still quite rare because they are difficult to grow without flaws.

Because lab-grown diamonds aren’t mined in remote locations, they cost less than naturally occurring diamonds. You can expect to pay about 40% less per carat, depending on the size and quality. That means they will generally cost thousands of dollars rather than less than $100 like a CZ.

Other Diamond Simulants

Crystal cut into gem shapes is inexpensive and widely available but it doesn’t look very much like diamonds. No matter how good the crystal, it has a low refractive index, which means that light travels through it instead of being reflected back as brilliance. If you put cut crystal on a newspaper, you can read right through it. In antique jewelry, you’ll sometimes see crystal backed with metal or foil to make the glass reflect more light back.

White sapphire is another diamond look-alike you see in vintage jewelry. Natural colorless sapphire is more affordable than blue sapphire but it doesn’t really look like diamond: it has less sparkle and brilliance. Lab grown sapphire is widely used today for watch crystals and supermarket scanners because it is much more durable than glass. Lab-grown white sapphire is still used as a diamond substitute today in inexpensive birthstone jewelry and class rings.

Moissanite is the crystal form of silicon carbide. This diamond simulant was first grown in the lab in 1993. It has a very high hardness of 9.2 so it’s durable. It has a high refractive index and very high dispersion, giving it lots of rainbow fire. It’s doubly refractive, which means you can see some doubling of facets. It also is often not quite white: it often has a slight green or brown tint.

When comparing moissanite vs CZ, moissanite is much more expensive. That makes it a less popular diamond simulant than CZ overall. Most sellers charge hundreds of dollars per carat for moissanite. 

When comparing moissanite to lab-grown diamond, moissanite doesn’t look identical to diamond like lab-grown diamond does. Moissanite is less expensive than lab-grown diamond. Moissanite is lighter than diamond, so a moissanite the same size as a one-carat diamond will weigh 0.88 carats.

What is the Best Choice for You?

If you are looking for a diamond simulant, cubic zirconia offers the best imitation of diamond at the lowest possible price. But if you are looking for diamond but prefer not to choose mined diamonds either for ethical or financial considerations, lab-grown diamonds have all the beauty of real diamonds and cost significantly less.