Diamonds vs Cubic Zirconia: What’s the Difference?

Diamonds vs Cubic Zirconia: What’s the Difference?

1st July 2021

Paying a high price for a natural diamond is unjustifiable to some which is why many turn to more ethical lab-grown diamonds, moissanite or even cubic zirconia. But, how does cubic zirconia compare to a diamond? While they may look similar from a distance, they differ greatly in structure, appearance and value. 

It’s vital you understand the differences between the two gems before making the decision to purchase one. Here, we’ll be exploring the biggest differences and how cubic zirconia stands up against the diamond for an engagement ring.

What is Cubic Zirconia?

Cubic Zirconia is an inexpensive synthetic gem made from the cubic crystalline of zirconium dioxide. While this stone can be found in nature in very small amounts, it’s extremely rare and so you can be sure that all cubic zirconia jewellery is made in labs. 

Technically discovered in 1892 it wasn’t until 1937 where German mineralogists found that melted zirconium oxide contained cube-shaped crystals. In the 1970s cubic zirconia was first used in fashion jewellery and has been incredibly popular since. Available in a wide range of shapes and sizes and a rainbow of hues from brilliant white stones to vivid red and blue, cubic zirconia has an aesthetically pleasing appearance and a distinct physical structure.

The Differences Between Diamonds and Cubic Zirconia

Even though cubic zirconia is one of the leading diamond replicas available, it’s surprisingly easy to tell the difference between the two - especially if you have diamond and a cubic zirconia side by side. Their durability, colour, clarity, brilliance and price are vastly different from each other which can really impact your decision when it comes to buying one.


It’s well known that diamonds are the hardest known naturally occurring material in the world with a ranking of 10 on the Mohs Scale of Hardness. This means that they do not get scratched or chipped easily and only a diamond can damage another diamond. Because of how extremely durable they are, diamonds are a great choice for engagement rings and everyday wear. 

Cubic zirconia receives an 8.5 on the Mohs scale which does make it a hard stone but it can be much more easily scratched and damaged. While it can be worn as jewellery every day it won’t have the superior longevity of a diamond and you may notice it turning cloudy over time too.


When it comes to diamonds, a colourless stone is the most desired because of its rarity and beauty. However, colourless diamonds are very expensive and often unattainable, unless you’re happy to spend tens or even hundreds of thousands of pounds. Diamonds are graded on the GIA colour scale which ranges from D (the best) and Z which is usually light brown or yellow. Realistically, when shopping for a quality diamond in a more reasonable price range we’d recommend looking for diamonds in the G to I range.

Because cubic zirconia is lab-created, the colour is able to be controlled. This means you’ll almost always find colourless cubic zirconia jewellery that’s similar to the D grade of a diamond. Of course, for many consumers, this is a very appealing trait as they’ll sparkle beautifully. However, often they can reflect an orange-tinted light which is a big giveaway that it’s not a real diamond.


Clarity is a very important factor to consider when you shop for natural diamonds as it can greatly impact their value. There are a wide variety of clarity grades from flawless to included. Needless to say, flawless diamonds are the rarest and therefore the most expensive, whereas included diamonds are of a lower quality generally. As a flawless diamond is difficult to come by, diamonds with a clarity grade of ‘VVS’ or ‘VS’ are the next best thing as it’s impossible to see any blemishes and inclusions with the naked eye.

These inclusions are how many can tell apart diamonds from cubic zirconias as, just like with the colour, cubic zirconia can be created to have excellent, flawless clarity. Though the idea of getting a colourless, flawless-looking cubic zirconia may seem great, some people feel they look too perfect and fake-looking. The tiny inclusions in a diamond are what makes it authentic and unique.


The sparkle and brilliance of a diamond, either natural or lab-grown, is unmistakable and a huge reason as to why they’re so greatly desired. Although many synthetic diamond replicas, such as cubic zirconia, have tried to capture the dazzling brilliance of the diamond, none have come close. A diamond's sparkle comes from three different types of light. The white flashes you see in sunlight, for example, is the brilliance. Coloured flashes are referred to as the fire. And the surface sparkle is the scintillation. 

Cubic zirconia contains no brilliance or fire as the light passes through the stone much differently and so there is significantly less reflection back. Instead, they have a very pronounced rainbow effect which makes it very easy to tell that it’s not a real diamond. When looking at the two stones under a light, you’ll be able to immediately see the difference for yourself.

Cost and Value

It should come as no surprise to learn that diamonds will always cost more than cubic zirconia. Where the cheapest diamonds will still set you back a few hundred pounds, the cheapest cubic zirconia jewellery you can get for as low as £10. This is because cubic zirconia is not a precious stone, it’s seen more like costume jewellery than anything else. 

Cubic zirconia also holds no second-hand market value after it’s been bought either. This is not a stone you should buy as an investment piece as once they have been bought they are seen as worthless, whereas diamonds can increase in value over time.

Is Cubic Zirconia Good for Engagement Rings?

Cubic zirconia should not be used for an engagement ring unless someone is on a very tight budget. As a less durable, less dazzling and less valuable stone, they won’t provide the longevity needed for an engagement ring. Typically this stone is used more for fashion jewellery or younger couples wanting to promise themselves to each other. For engagement or wedding rings, natural and lab-grown diamonds will always be the better choice.

Browse our stunning range of ethical lab-grown diamond rings that are lovingly crafted and ideal for engagement rings or wedding bands.

If you’re considering moissanite as a diamond alternative, read our guide on moissanite vs diamonds to learn everything you need to know about the two.

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