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Cubic Zirconia Vs. Diamond: What’s The Wiser Choice?

Cubic Zirconia Vs. Diamond: What’s The Wiser Choice?

Cubic zirconia appears similar to diamonds, sometimes to a miraculous extent. But while they might shine bright, there are a few flaws that remain hidden out of sight – at least at a glance. 

How is cubic zirconia formed? Could the average individual even spot the difference between real diamonds and CZ? How do they compare in terms of other properties? Which one lasts longer?

That’s a long list of questions to answer, huh?

All this – and more – will be covered in this guide. So, be sure to keep scrolling, and let’s find out who is the winner in the never-ending battle – cubic zirconia vs. diamond!

What Is A Diamond? What Is A Cubic Zirconia?

Cubic zirconia has long been the synthetic substitute of choice for natural diamonds. That said, there are some considerable differences between the two – starting with the way they’re made. 

Where Do Diamonds Come From? 

Diamond is a mineral composed of carbon, making these precious stones the hardest naturally occurring substance known to humankind; only another diamond can scratch it.

They are formed in a very hot place, deep within the Earth – about 100 miles below the surface. 

Those high temperatures and the pressure of surrounding rocks, pulled by gravitation towards the Earth’s core, are fundamental forces for growing these crystals. 

We can’t know more about the complete process since there is no way to sample this part of the Earth.  

But how did we get to the diamonds themselves?

They’ve been brought to the surface through strong volcanic eruptions. Scientists believe it was pretty violent, and it occurred a long time ago – when our planet was much hotter. 

And just in case you were wondering, no, lava isn’t technically hot enough to melt diamonds – although that calls for a whole separate discussion. 

This mound of volcanic material, called Kimberlite, ruptured the Earth’s surface and eventually cooled – with the diamonds still in them. It had to have happened within hours – otherwise, the diamonds would have transformed into graphite under such temperatures. 

That means they were traveling 20 to 30 miles per hour, and they cooled down so quickly, they didn’t retain energy long enough to rearrange the diamond carbon atoms into graphite – and just locked into place!

The bond formed between carbon atoms under such pressure is so strong that one atom makes covalent bonds with four others at the same time. And that’s what makes diamonds so hard.

As mentioned, we can only guess where the carbon comes from – but the atoms have to be very close in order to form these strong bonds. 

Read More: Can You Find Diamonds In Lava Rock?

Where Does Cubic Zirconia Come From?

CZ – short for cubic zirconia – is pretty much described by its name. It’s a synthetic gem made of zirconium dioxide or, rather, its cubic crystalline form. 

Now, we get how this might be confusing, but don’t confuse it with zirconium – a silver-grayish metal known for being easily malleable and ductile and highly resistant to corrosion. So, just to make sure we’re all on the same page about this: 

Cubic zirconia is a cubic crystalline form of zirconium dioxide (ZrO2) and shouldn’t be mistaken for zircon or, more specifically, zirconium silicate (ZrSiO4). 

But while cubic zirconia is a synthetic diamond simulant, it’s worth noting that the natural form of zirconium oxide – known as baddeleyite – was discovered back in 1892.

What Is Baddeleyite?

Baddeleyite is a synonym for zirconium dioxide – a naturally occurring form of zirconia mined in the United States, Australia, Brazil, South Africa, Russia, and Sri Lanka. 

Now, what does that have to do with CZ? Well, we figured it’s worth pointing out the differences between the two while we’re at it: The difference between baddeleyite and cubic zirconia comes down to how the zirconium and oxygen atoms are arranged. 

The former is a monoclinic crystal, while the latter is cubic (isometric), boasting the same crystal structure as diamond. That makes CZ extremely hard – but we’ll get to that later. 

That being said, we have to ask – is CZ considered a real gem?

Is Cubic Zirconia A Natural Gem? 

Even though it might seem diamond-like, the answer is no. That said, gemstones are divided into three groups:

  • Natural: Cut from different minerals of crystalline, such as diamonds or quarts; also include organic material, such as fossil, amber, coral, or pearls
  • Synthetic: They are laboratory-grown and have the same appearance and chemical, physical and optical properties; they include emerald, ruby, sapphire, and many other gems
  • Simulant: They are also laboratory-grown and have a similar appearance as natural gems but have different optical, physical, and chemical properties. CZ is a part of this group 

Related Read: Are Cubic Zirconia (CZ) Diamonds Fake?

How Is CZ Made?

Now, as you might know, natural diamonds are mined in their rough state and then go through a lengthy process of cleaving, sawing, cutting, and polishing before they’re considered a “finished piece.” 

But what about cubic zirconia?

The primary ingredient, as we mentioned, is zirconium dioxide in powder form. It’s stabilized by magnesium, calcium and features certain additives to achieve a close-enough natural look. The amount of each ingredient differs, depending on the manufacturer. 

A specific melting system – called the skull melting system – is used due to the mineral’s high melting point.

Don’t worry; the “skull” refers to a paper cup – and water circulates through its hollow walls. It’s heated by radiofrequency until the powder put inside melts. The layer closest to the cup doesn’t melt, though, since it’s next to the cooling water – and it just surrounds the melted component.

After a cooling period, crystals form and grow until the melted part solidifies. The next step is cutting; that’s something that CZ has in common with diamonds. 

The cutter must determine which shape will produce maximum clarity and use of the crystal; that’s a part of the shaping process for all crystals.  

Are There Cubes In Cubic Zirconia?

The answer is YES! If there are sufficient zirconium dioxide crystalline forms, the molecules stack together in a cube shape – kind of like salt crystals.

So, no matter the shape of the CZ, the stone’s internal structure is always the same – it just has to be seen through a microscopic scale. 

Different Properties Of Cubic Zirconia & Diamonds – Comparison

Let’s see how the two hold up in a side-by-side comparison, shall we?


On the hardness scale, the CZ ranks within the range from 8.5 to 9, while genuine diamonds get a perfect 10. They are the hardest natural substance known to man, after all. 


Another factor to consider is brilliance, or to put it simply, the amount of white light bouncing off the surface of the gem and returning to the eye of the observer. 

The reflective index is the ability to reflect a light ray into colors of red, orange, green, yellow, violet, and blue. CZ holds an index of 2.15-2.18, while a genuine diamond has a higher value – 2.42, to be precise.

There are some exciting effects that this high index can bring, but we’ve covered that in another article. You’re welcome to check it out! 

This difference indicates that cubic zirconia has no real brilliance or fire-colored light reflection – and, in that sense, can’t compare to a diamond sparkle-wise.


Just like both gems can be formed into various shapes, they come in similar colors. The colors range from palest yellows to brilliant reds.

While the color of diamonds usually depends on the cut and their formation, variations in oxide mixtures have the same effect in CZ. Both result in an unwanted, uneven coloring of the stone.

When it comes to genuine colored gemstones, such as topaz, amethyst, and ruby, their optical constants have low values. 

That’s considered a flaw, though, since the color is a highly appreciated feature in these gems. The discovery of cubic zirconia was when the color and brilliance were finally combined.

Cubic zirconia is colorless and, if made right, has no inclusions. Most consumers – and experts – agree that it can seem “too perfect,” though. 

That’s why some manufacturers even started producing colored tints and inclusions as a way to make them resemble diamonds more.


There’s a notable difference in density between real diamonds and cubic zirconia, with the latter being 1.7 times denser. 

That implies that the dimensions of a one-carat diamond won’t match those of a one-carat CZ. So, if you had a CZ gem that matched the weight of a one-carat diamond, it would be smaller – because it’s more dense. 

For more on carats, take a look at the following article.


The cut is the most important when it comes to a gem’s properties that determine value. 

In 1919, Marcel Tolkowsky, a third-generation diamond cutter, determined the ideal proportions at which a diamond should be cut to obtain maximum fire and brilliance. 

It’s called the brilliant cut and is still used as the most objective, measurable standard. One stone has 58 facets, cut in mathematically-determined angles to maximize light reflection. 

The proportion and finish grades of a gemstone are defined by the degree of deviation from this standard – and this applies to both diamonds and CZ. 


Next, we have the clearness or transparency of the gem. 

This property is determined by nature for diamonds – trace minerals and similar imperfections. The general rule is: The clearer the stone, the more valuable it is.

But for CZ – which is lab-made – only variations in the oxide mixture can produce slight random inclusions. That’s just bad laboratory work, though. Otherwise, these simulant gems are perfect – too perfect, some might say.

Related Read: Diamond Clarity Chart: Everything You Need To Know


Although there are many, the classic round shape offers the best dispersion, brilliance, and fire in CZ – as well as diamonds. 

Read Also: Which Diamond Shape Is Best? Guide To Popular Diamond Shapes

CZ Vs. Diamonds: Value Differences

There are a few more facts you need to know that can affect the value difference between the two rival gems:

  • First comes the time of origin. Diamonds originated anywhere from the first couple billion years of the Earth – to “just” tens of hundreds of millions of years. Scientists determine the age of the gem through mineral inclusions. On the other hand, the CZ has been on the market since 1976.
  • Moissanite is the second-best replacement for a diamond, next to the cubic zirconia. It’s been around since 1998 and is now the biggest rival of CZ since it looks more similar to a diamond in both composition and appearance. But it has the same problem as cubic zirconia – it can seem “too perfect.”
  • It’s unknown how long it takes for diamonds to form in nature – maybe it takes millions of years since it’s not a continuous process and could pause with the change of conditions. On the other hand, Cubic zirconia can be created within a short period – under controlled lab conditions.

If there’s one thing you can take from the information above, it would be this: The difference in how they’re made is the leading reason diamonds can cost from a few to tens of thousands of dollars per carat, while a nice cubic zirconia costs from a few tens to a hundred dollars per carat.

Cubic Zirconia Vs. Diamond – Is The Difference Visible?

There is one trick you can use at home if you’re looking for a visible difference between a real diamond and cubic zirconia. 

The best way to differentiate one from the other is to look at the stones under natural light. The diamond gives off a white light (brilliance), while the cubic zirconia gives off a rainbow-colored light – called excessive light dispersion.

But both can scratch glass if you were contemplating this method!

There are other reliable methods for testing a diamond, including using a diamond tester to check a gem’s thermal or electrical conductivity. That said, keep in mind that, in some rare instances, these nifty gadgets could be fooled

Learn More: How Can You Tell a Diamond From a Cubic Zirconia?

Bottom Line

By now, you’re undoubtedly aware of every difference needed to decide which rival to choose in the neverending contest of cubic zirconia vs. diamond.

Cubic zirconia can have an intense colorful sparkle, perfect clarity, and almost any color. Most importantly – it’s affordable to an average person. On the other hand, diamonds have a timeless reputation, guaranteed uniqueness – and last “forever.” 

That means that if you don’t mind the origin of your gem and don’t wear it often, then the choice solely depends on your taste!

If you’re still hesitating, the cubic zirconia was deemed “good enough” to create a perfect replica of the notorious Hope Diamond. It still stands next to it at the Smithsonian Institute as we speak. 

That says something about these diamond simulants

Related Read: Moissanite Vs. Cubic Zirconia Vs. White Sapphire