Diamond Vs. Cubic Zirconia (CZ) - Buying Guide

Cubic zirconia (CZ) and diamonds may look similar at a distance, but differ drastically in beauty, quality and value. For a stunning engagement ring that will last a lifetime, we recommend choosing a real diamond over cubic zirconia. While you can find a cubic zirconia ring for a fraction of the cost of a diamond ring, the diamond is a far superior option.

While the two stones carry some resemblance, cubic zirconia and diamonds differ significantly in physical structure, beauty and value. Before deciding on an engagement ring or other fine jewellery, be sure to understand the key differences. This guide offers a full comparison of cubic zirconia vs diamonds, for everything from beauty and brilliance to cost and durability.



Cubic Zirconia

Cubic Zirconia.

Diamond vs. Cubic Zirconia.

Cubic Zirconia (CZ)

Cubic zirconia is a colorless, synthetic gemstone made of the cubic crystalline form of zirconium dioxide. Cubic zirconia can appear in nature within the mineral baddeleyite, although it's extremely rare. In all cubic zirconia jewellery, the gemstones are exclusively lab-created.

Often regarded as an inexpensive diamond alternative, cubic zirconia is distinct in its aesthetic qualities and physical structure because it's lab-grown, whereas natural diamonds are beautiful, naturally occurring gemstones.


Cubic zirconia is made in a laboratory from a mixture of zirconium oxide powders stabilized with calcium and magnesium. The exact process depends on each specific lab. Cubic zirconia can mimic various diamond shapes, such as cushion cut and oval cut diamonds. Colored versions of cubic zirconia are also available.

Diamond Vs. Cubic Zirconia Colors

Diamond vs. Cubic Zirconia colors.

As a synthetic gemstone, cubic zirconia comes in a large array of colors, from colorless to black. The wide color range is caused by coloring agents added to the source powder during the growth process.

If the coloring agent is caesium, the cubic zirconia turns yellow, orange or red depending on the concentration of the microelements. In the case of copper, iron. nickel and titanium, we get yellow. amber and brown colors.

Lilac, violet, purple and blue cubic zirconia is caused by various combinations of cobalt, manganese and neodymium microelements. The pink color is due to the presence of erbium, europium and holmium, while green is caused due to chromium, thulium and vanadium.

Cubic Zirconia Properties

Chemical Name Zirconium dioxide
Chemical Formula ZrO2
Crystal System Cubic
Colors Colorless, yellow, orange, amber, brown, pink, red, lilac, violet, purple, green, blue and black
Hardness 8.25 - 8.50 on the Mohs scale
Refractive Index 2.171 - 2.177
Specific Gravity 5.65 - 5.95
Transparency Transparent
Birefringence None
Lustre Vitreous
Cleavage None
Fluorescence Yellow, greenish yellow or beige

Cubic Zirconia properties.


Cubic zirconia is significantly cheaper than diamonds. For example, a 1.50 carat princess cut cubic zirconia ring can retail for around $40, whereas a 1.40 carat princess cut diamond ring (with excellent clarity, cut and color) costs around $10,000. As carat weight increases, the price gap only becomes larger. For instance, a 3.00 carat cubic zirconia ring may sell for around $200, while a 3.00 carat diamond ring with acceptable cut, clarity and color may sell for around $25,000.

From a value standpoint, cubic zirconia is worth next to nothing. If you were to try and resell a cubic zirconia engagement ring, you could perhaps retain some value for the setting. The cubic zirconia gemstone, just like other diamond simulants, carries no market value.

A diamond, on the other hand, does retain some of its market value. Unlike cubic zirconia, though, diamonds can also be passed down for generations as a family heirloom and keepsake. Diamonds carry a certain prestige because they are stunning, natural gemstones with a timeless appearance. Overall, a diamond's price and value are dependent on its 4Cs (Cut, Color, Clarity and Carat). These elements work together to form the beauty and brilliance of the stone.

While price differs significantly between diamonds and cubic zirconia, it's essential to realize that so do the physical features, quality and beauty. In this case, a lower price does not mean a better value or deal.

Diamonds & Cubic Zirconia - The Difference

There are several ways to tell the difference between diamonds and cubic zirconia, including their physical, chemical and visual properties. Knowing the key differences will help you make the best decision when designing and purchasing jewellery.

Beauty & Brilliance

The quality that most greatly affects a diamond's beauty is its cut, which impacts how much light reflects through the diamond's table to your eyes. White light reflection is referred to as brilliance and colored light reflection is called fire.

Cubic zirconia contains no true brilliance or fire. It has a much lower refractive index, between 2.15 - 2.18, compared with 2.42 for diamonds. Light passes through cubic zirconia much differently, offering significantly less reflection back to the eye. By simply looking at the two gemstones under a light, you can tell the immense difference in light reflection.

Cubic zirconia also has a higher dispersion rate (between 0.058-0.066 compared with 0.044 of diamonds). The increased dispersion causes the CZ stone to have a "rainbow effect," meaning it reflects too much colored light. The excess dispersion of light makes it easy to spot as a fake diamond.

Overall, cubic zirconia is no comparison to the unmatched beauty and brilliance of a diamond.

Durability & Density

As the hardest naturally occurring mineral in the world, diamonds rate a perfect 10 on the Mohs scale of hardness. Diamonds are incredibly durable and resilient, making them ideal for engagement rings and everyday wear. Diamonds maintain their sparkle and beauty with minimal maintenance.

Cubic zirconia, on the other hand, ranks an 8.5 on the Mohs scale of hardness. Because it's a synthetic material, it offers some durability. It can be worn in jewellery, but will certainly not have the longevity of a diamond. For example, cubic zirconia becomes scratched and cloudy over time.

Cubic zirconia is also slightly denser than diamonds. A jeweller or gemologist can easily distinguish a CZ stone from a diamond by weighing it on their scale. A 1.00 carat diamond, then, will likely appear slightly larger than a 1.00 carat cubic zirconia, depending on the gemstone's shape.

Clarity, Cut & Color

Since cubic zirconia crystals are created in labs, they are usually internally flawless (IF). This makes them very attractive to many buyers around the world. However, this is also one of the main ways to tell CZ and diamond apart as no diamond is perfect.

Cubic zirconia has a much lower refractive index (2.17) than a diamond (2.417 - 2.419). This means when cut and polished, it does not show true brilliance and fire because light passes through CZ much differently.

Cubic zirconia can be found in all traditional shapes and cuts, the most popular being round.

The cut quality of cubic zirconia is graded through the A rating system. which only applies to mass-produced machine cut stones. Rated from A or 1A to AAAAA or 5A. 1A is considered the lowest quality of machine-cut CZ, while 5A is the best possible quality.

Hand-cut cubic zirconia stones are of much higher quality, which is why they are not graded through the A system. However, it is important to mention that the quality of hand-cut stones depends on the cutter's technique and experience.

As mentioned, because cubic zirconia is made in a lab, it lacks the natural imperfections that diamonds have. A flawless diamond is incredibly rare and, thus, incredibly expensive. While some may regard cubic zirconia as flawless, they're usually considered "too perfect" or fake looking.

If you're looking for a diamond, we recommend finding one that's eye-clean, meaning you can't see inclusions and blemishes with the naked eye. Depending on the carat weight, this generally means opting for a VS1 or VS2 clarity grade. While you could choose a higher clarity grade, you'll be paying for a feature that will go unnoticed. By selecting an eye-clean diamond, you'll have a stone that looks practically perfect to the naked eye.

When it comes to diamond color, we recommend finding a diamond that appears white in relation to its setting. Based on your diamond shape and the type of setting, we generally recommend looking for a diamond in the G to I range. Cubic zirconia is considered colorless because it's manufactured that way. These synthetic stones, however, often reflect an orange-tinted light, which is another clear indicator that it's not a real diamond.

Final Thoughts

By both experts and non experts, cubic zirconia should not be considered a diamond under any scenario. For many reasons, from chemical properties to brilliance and color, the two stones are entirely different.

Diamonds are naturally found, formed of the hardest material and possess extraordinary beauty. Cubic zirconia is lab-created. The stones lack brilliance and lasting beauty. Because diamonds and cubic zirconia are unmistakably different in beauty and quality, we cannot recommend cubic zirconia jewellery.