Diamonds Vs. Cubic Zirconia: What’s the Difference?

Cubic Zirconia (commonly referred to as CZ) is one of the most popular diamond simulants in the jewelry industry. Since commercial production of cubic zirconia began in 1976, it has been a popular choice for those who can’t afford the high price of diamonds.

Cubic Zirconia vs Diamond – How They’re Made

Cubic Zirconia vs Diamond

The process of creating cubic zirconia is done in a controlled laboratory environment. Manufacturers produce it by mixing pure zirconium oxide powders stabilized with calcium and magnesium. The powders are melted at extremely high temperatures, after which the cubic zirconia crystals form as the mixture cools.

The “cubic” in cubic zirconia refers to the cubic arrangement of atoms after the mixture has cooled, and this atomic arrangement is vital in giving it properties similar to diamonds. Cubic zirconia is colorless, but manufacturers can alter its appearance using various techniques.

Diamonds are natural gemstones formed almost 100 miles beneath the earth. They are the result of applying extremely high temperatures and pressures to pure carbon for 1 – 3.5 billion years. Nowadays, manufacturers can simulate this process in controlled environments, allowing them to create diamonds in months.

Cubic Zirconia and Diamonds – Physical Properties

Cubic zirconia is a denser stone than diamond, measuring between 5.6 and 6.0 g/cm3; the density of diamond measures around 3.5 g/cm3. As a result of the disparity in density, a cubic zirconia stone of the same size as a diamond would be heavier.

The hardness of a stone measures how resistant it is to scratches, and cubic zirconia scores an impressive 8.5 on the Mohs scale of hardness. Diamonds are the hardest naturally-occurring substance on earth and score a perfect ten on the Mohs scale. 

Because diamonds are formed naturally, they have imperfections in them. These imperfections are known as inclusions, and jewelers use them to measure a diamond’s clarity. On the other hand, cubic zirconia stones rarely have any inclusions and appear similar to D-grade diamonds in clarity.

Cubic zirconia insulates heat well, so a CZ stone should feel warm (like glass) when you put it on the tip of your tongue at room temperature. Diamonds are great thermal conductors and feel cool (like metal) when you place them on the tip of your tongue in the same circumstances.

Which is Better Cubic Zirconia or Diamond?

Diamond is by far a more popular stone than cubic zirconia; however, the popularity of a stone doesn’t guarantee that it’s superior. You can make your choice of either stone based on two factors– price and appearance.

1. Price

One of the biggest differences between diamond and cubic zirconia is the price. Diamonds have always been reserved for the wealthy because every stone is expensive. 

Cubic zirconia is one of the jewelry industry’s ways of meeting a rising middle-class population’s need for diamond lookalikes. They were made to meet the needs of people who wanted the bling of diamonds but didn’t have deep enough wallets.

A one-carat cubic zirconia stone will cost $20, and a 2-carat stone, $30. Diamond prices are way higher, with a range between $2,000 a $25,000 for a single carat stone. The differences in diamond prices reflect the different qualities of each stone.

2. Appearance

The 1.5 difference in hardness between cubic zirconia and diamond might look insignificant on paper. However, it becomes telling as you subject your jewelry to the rigors of daily use. 

The refractive index of a stone measures how much the stone disperses light as it passes through. The Refractive index gives the “fire” effect of a gemstone. Diamonds have a refractive index of 2.42, while cubic zirconia’s refractive index is 2.15-2.18, causing them to glitter less than diamonds.

Diamonds are nearly impervious to scratching, and you can only scratch a diamond with another diamond. Cubic zirconia scratches more easily, and you’ll observe the effects of daily use on your stone, as even household dust can scratch it. When you expose CZ to oils and beauty products, even the most brilliant stones will scratch and become murky with extensive use.


Cubic zirconia is a beautiful stone in its own right; however, it doesn’t compare to diamonds’ classic beauty and value. A higher reflective index and an intricate pattern of dispersing light make them a superior stone in appearance to CZ.

If price is the ultimate determinant of what you want to buy, then cubic zirconia is the sure way to go. Since the stones are so cheap, you can replace your worn-out stones without sweating at the bill. However, you’ll always be better off buying diamond jewelry since diamonds are forever.

Cubic Zirconia vs. Other Diamond Simulants

While cubic zirconia is arguably the most popular diamond simulant, other alternative gemstones look like diamonds.

1. Cubic Zirconia vs. Lab-grown Diamonds

Lab-grown Diamond
Lab-grown Diamond

The desire to create an alternative to natural diamonds has existed since the late 18th century. Before scientists thought to try creating simulants like cubic zirconia, they attempted lab-grown diamonds. However, there was no success in that regard until 1954.

Today, the lab-grown or synthetic diamond market is growing rapidly. Synthetic diamonds have all the characteristics of natural diamonds, but they’re created in a fraction of the time. Synthetic diamonds cost a fraction of a natural diamond’s price because they aren’t as rare.

Cubic zirconia is certainly cheaper than a synthetic diamond. However, since a synthetic diamond has the exact attributes of a natural diamond, you would love them if you loved natural ones.

2. Cubic Zirconia vs. Moissanite

Emerald Cut Moissanite Ring
Emerald Cut Moissanite Ring

Moissanite is another diamond simulant that has kept growing in popularity. Charles & Colvard started producing them in the late 20th century, and they play an important role in the jewelry industry.

Measuring 9.5 on the Mohs scale, moissanite is a harder stone than cubic zirconia, second only to diamonds. Moissanite has a distinctly high refractive index of 2.65, causing it to have more fire than diamonds. 

Moissanite costs more than cubic zirconia but far less than natural diamonds and is a more lasting stone than CZ.

Carat SizeGIA Certified Diamond (Round, I-color, VS2)Classic MoissaniteNear Colorless MoissaniteForever One Colorless MoissaniteCubic Zirconia

Source: Do Amore

3. Cubic Zirconia vs. White Sapphire

White Sapphire ring
White Sapphire Ring

Sapphires are one of the oldest known gemstones. These beautiful gemstones are available in various colors, and lower demand causes white sapphires to be cheaper than blue, pink, and yellow sapphires.

White sapphire measures 9 on the Mohs hardness scale, and diamonds are the only natural gemstones harder than it. White sapphire is, therefore, a more durable gemstone than cubic zirconia. Like the other diamond simulants, high-quality white sapphire costs less than diamonds but is pricey compared to cubic zirconia.

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