Cubic Zirconia VS Moissanite And The Great Diamond Debate

Cubic zirconia is a very pretty man made gemstone in its own right – as is moissanite but ask anyone about diamond and you will hear real passion in their voice!

A well cut cz or moissanite really should be judged on their own merits rather than as diamonds replicas. The biggest differences are the relative hardness and optical properties between the three as well as the relative financial values.

As all gemstones are ultimately compared to diamond, what are the real differences between cubic zirconia and moissanite and how do they really compare to diamond?

Cubic Zirconia


Cubic Zirconia, contrary to public belief, can be found in the natural world but is extremely rare. Cz was first discovered in 1937 by two German minerologists but in very minute quantities.

It wasn’t a significant find and was soon forgotten. Then in the early 1970′s Russian scientists began to grow it in laboratory conditions, not for jewelry making but for industrial use and space technology.

Because of its similarities to mineral gemstones it wasn’t long before attention was focused on the jewelry possibilities of this new man made material.

Cubic Zirconia VS Moissanite And The Great Diamond Debate


Cubic zirconia is an oxide of the metallic element – Zirconium (ZrO2). In colored forms of Cubic Zirconia oxides of other metals such as copper, iron, nickel and many others are added in varying degrees.

CZ is mostly an amalgamation of approx 87% zirconium oxide and 13% yttrium oxide although different “recipes” are used all over the world.

The quality of the stone is usually influenced by the high heat induced formation process by the type and quantity of the stabilizing material that’s needed to “bond” the cubic zirconia atoms after cooling.

Some cubic zirconia can suffer optical degradation in that the stone either discolors or clouds over time, whereas other forms will remain clear and transparent.

Gemstone Relationships

Cubic zirconia is fairly hard, and is harder than quartz gemstones such as amethyst, but is softer than topaz ruby and sapphire – and of course diamond. Cubic Zirconia scores an impressive 8.5 on the Mohs scale but is not resistant to wear and chipping and does require care by the wearer.

Cubic Zirconia’s best properties are its light and it’s relative cheap financial value. To the untrained eye, cubic zirconia looks identical to diamond and can fool plenty of so called “knowledgeable ” jewelers. It can also fool unsuspecting buyers who might think they are buying diamond!

So how can you tell them apart?

Diamond Differences

The biggest giveaway is weight. A 1 carat diamond weighs 1 carat. A comparable sized (in volume) cz weighs 1.75 carats. A cz can be scratched by diamond, topaz, ruby or sapphire whereas a diamond can only be scratched by another diamond.

The optical differences make comparisons between these two stones very interesting. A diamond displays more brilliance, whereas a cubic zirconia has more fire (disperses light further, see picture).

Even though a cz has more fire, it is far more intense than a diamond’s fire which shows a more color balanced “natural” fire.

The difference in brilliance and fire is caused by lesser amounts of light being reflected back from the inside of a cubic zirconia stone.

Basically a cubic zirconia has a smaller refractive index which causes light to bend at a much shallower angle and therefore more light is lost through the stone rather than being reflected back from it.

This probably accounts for some of the extra fire.

Over time a the comparatively softer cz stone may wear along its prominent edges and this in turn will spoil some of the optical properties.

The other big difference to consider is that 99.9% of diamonds are imperfect in some way or another and this adds to their overall character and cannot be easily be reproduced by cubic zirconia.

A colorless diamond is extremely rare – they usually have some kind of yellowish tint which on most occasions isn’t apparent to the naked eye – a cz on the other hand is almost perfectly transparent.

Cubic Zirconia’s biggest flaw as a diamond simulant? It’s just too perfect! The other big problem with cubic zirconia is the quality of the cut. Cheap czs are always machine cut, while a more expensive cz will have been worked on by human hand to produce the best possible cz gemstone.

All in all when adding up the differences we can see that each stone should be appreciated in its own way.


Cubic Zirconia VS Moissanite And The Great Diamond Debate

Moissanite is a very new contender in the man made gemstone arena. It’s similar though not entirely the same as cubic zirconia.


Moissanite is not found in the natural world as large crystals suitable for jewelry. It was found in the fragments of a fairly large meteorite by Henri Moissan in 1893. The material was named after him in 1905.

Fast forward 90 years and the first man made moissanite was manufactured and explored for cutting into gemstone shapes. By 1998 full scale production began.

Moissanite as a gemstone is exclusive to Charles and Colvard Jewelery manufacturers and Cree – a USA based research and development lab who first researched the material for industrial use.

As with Cubic Zirconia a lot of so called “professional” jewelers can’t tell them apart from diamond without the aid of specific tests.

Natural moissanite is very green in color and so is its man made counterpart and it can also fluoresce green when exposed to strong sunlight. This is in huge contrast to lesser color diamonds which have a yellowish rather than green tint. Colorless moissanite doesn’t yet exist.

A moissanite’s fire vastly surpasses that of a diamond, in fact more than twice! Ultimately that’s what’s so appealing about moissanite’s quality as a jewel.

Unlike diamond and cubic zirconia, moissanite handles light differently and produces bi-refringance or double reflections which goes some way to explaining its higher brilliance (reflected light) when compared to diamond.

This can help hide color in smaller round brilliant cut moissanites although the cutting of moissanite requires slightly different methods and faceting.


Moissanite is the crystalline form of Silicon Carbide (SiC) and is formed with the aid of high pressure and heat. Since Diamond is essentially 99.9% carbon, moissanite is pretty close though no where near identical to diamond (how weird does that sound?).

Moissanite has a value of 9.25 on the mohs hardness scale which makes it second only to diamond in gemstone terms. Diamond can be up to 20 times harder than moissanite although moissanite is considerably tougher than diamond along the planes of a diamond’s cleavage.

Moissanite is also considerably more heat resistant than diamond although quite how this affects it’s use in jewelry and the day to day wearing of such jewelry is pretty much irrelevant.

One more factor in the equation are reports that moissanite has a different structure to diamond and has a higher tendency to chip along its edges than diamond does.

This suggests it’s more brittle than diamond although we could find no specific information to corroborate this theory.

Diamond Differences?

When compared to diamond, a moissanite’s character of brilliance is a less focused or more fuzzy effect which adds warmth rather than ice to the look and feel of the stone.

Weight for weight, moissanite is slightly lighter than diamond and much lighter than cubic zirconia. Moissanite is also reported to be imperfect in its formation in similar ways to diamond.

It can exhibit inclusions and other clarity degrading properties that can either add character or detract from value.

When we add up all the facts we find that moissanite is a very poor diamond simulant but is an extremely pretty man made gemstone in its own right. If we look closely then cubic zirconia is much closer to diamond than moissanite will ever be.

Cz Vs Moissanite

Whilst cubic zirconia can lack some character, especially machine cut cz, moissanite is always human cut but its gem properties are far too over the top to be considered a good diamond simulant.

Its strengths definitely lie in its own ability to sparkle like crazy and stand out from the crowd!

There is also a price difference between the two stones. Moissanite has been heavily marketed as a “jewel like no other” not particularly obvious in its direct competition with diamonds, but nevertheless there is a direct marketing connection and competition with diamond jewelry.

This and the fact that it’s hand cut and exclusive to Charles and Colvard means that this jewel commands a premium price that Cz won’t ever attain unless it’s ever renamed and rebranded.

Moissanite is still much cheaper than diamond but it’ll never replace the ice stone, especially if De Beers (world famous diamond brokers) have anything to do with it.

Cubic Zirconia on the other hand when cut by man does command a premium over machine cut stones, after all plenty of man hours go into the cutting processes and a very fine gem is produced at the other end.

Cz’s a gem to rival diamond on price and beauty and a gem to rival moissanite as a more believable diamond simulant.


If you have the money and an appreciation for a diamond’s qualities then you have to buy diamond . If price is a major concern then Cubic zirconia is the best option to consider.

If you’re concerned at all with diamond mining or conflict diamonds then there is a man made diamond alternative that you should see. It has ALL the properties of real diamond but it’s man made and it’s called Takara.

If you’re looking for an engagement ring but can’t afford real diamond then you simply have to take a close look at Asher . Asher is a form of cubic zirconia that has a hardness of 9 on the moh’s scale and is utterly fantastic when cut by man.

If you want something different or you simply want to show off then moissanite is the jewel for you.