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Moissanite vs Cubic Zirconia: the Beauty and the Beast

By moissanite

What is the difference between Moissanite and Cubic Zirconia? This question is not so difficult to answer given that both stones perform so differently in many respects. The main thing that they have in common is the fact that they are both man made stones. In addition, they are both diamond simulants, meaning that they try to mimic the look and feel of genuine diamonds.

That said, there is a huge difference between the two. If you want to skip reading the rest of the text, here is your answer right at the beginning. Cubic zirconia (CZ) stones are no real match for moissanite diamonds if compared across the whole range of features. The only advantage of cubic zirconia over moissanite that I can think of is their relatively low price.

To support the above claims, let us examine the physical and optical properties of both gems, step by step.

The Composition

Moissanite is silicon carbide, a compound with chemical formula SiC. On the other hand, cubic zirconia is zirconium dioxide, ZrO2. Moissanite is composed out of silicon and carbon, whereas CZ in its crystal lattice contains zirconium and oxygen. Diamond, as you probably know, is pure carbon. If you compare both of them to diamond, moissanite comes much closer. In fact, moissanite can be understood as being obtained by replacing some of the carbon atoms in the crystal structure of diamond with silicon. Even the local bonding is very much preserved, because silicon has the same valence as carbon and can be accommodated in the same environment. Cubic zirconia is much more different, as it contains zirconium, which is a relatively heavy element with totally different properties. This is why CZ has a higher specific gravity — around 6 — which is almost twice as much as moissanite's specific gravity of 3.2.

Crystal Structure

The crystal structure of Moissanite is hexagonal, with stacking order ABAC for tetrahedral structures. The structure of CZ (cubic zirconia) is obviously cubic. This as a consequence has the fact that moissanite is not isometric, and is doubly refractive, unlike cubic zirconia or diamond.

The double refractivity means that each light ray entering a double refractive crystal or gemstone is decomposed into two rays, unless the crystals are observed from a special direction called optical axes where there is no such effect. Moissanite is often cut in such a way that the table facet is perpendicular to its optical axis, so if you look at it from the top facet of the stone you won't see this doubling effect. On the other hand, it can be argued that the very same doubling effect contributes to the increased beauty of moissanite. i.e., it leads to high brilliance (refractive index) and fire (dispersion).

Optical Properties — Brilliance and Fire

Let us take a look at the optical properties of Cubic Zirconia and Moissanite, in particular, their brilliance and fire. The brilliance is closely related to the refractive index of the material. In case of moissanite it is around 2.7 which is considerably larger than the refractive index of diamond (2.4) or cubic zirconia (2.15). If you decide to buy a moissanite diamond we are sure you will appreciate this amazing property of moissanite. The brilliance simply tells you how much of the incident white light is being reflected back to your eyes. That feature is heavily dependent on the artistry of cutting and polishing. The brilliance of CZ obviously lags behind both diamond and moissanite. When it comes to their fire, that is, to their properties of dispersing light, moissanite has a dispersion of 0.1 which is considerably larger than 0.06 which is the value of cubic zirconia. In this case they both have larger fire than diamond with its merely 0.04. In practical applications this means that there will be more rainbows (colored light) in both moissanite and CZ than what you would see in diamonds.

CZ and Moissanite Rings

Color and Transparency

The cubic zirconia gems are perfectly transparent and perfectly white. That is one of their notable features, one that sets them apart from the other more valuable precious stones and simulants. Even if you are not trained in gemology, you will be able to tell CZ from moissanite or diamond. Due to the complicated process of production, moissanite diamonds are neither perfectly white and transparent, nor flawless. They often possess slight greenish or even yellowish hues, along with some imperfections in the structure. In this respect moissanite is more similar to diamond.

Recently some colored moissanite samples have appeared on the market. The colors range from a peach pink, canary yellow, and beautiful intense light green to dark green.

Durability

When it comes to durability, the durability of a gemstone is determined largely by its hardness. But, other factors can also come into play, such as internal strains in the structure, so be careful. Even though all three stones, moissanite, diamonds, and cubic zirconia, are relatively hard, that does not mean they are unbreakable. The hardest and most durable is diamond with the maximum possible hardness of 10 on the corresponding scale. Moissanite is dangerously close with 9.2, and the least hard of them is CZ with 8-8.5.

Another property worth examining is the toughness. It is the resistance to breaking. Cubic Zirconia has a very poor toughness when compared to Moissanite: 2.4 versus 7.6. Moissanite is almost three times tougher, i.e., three times more resistant to breaking and chipping.

Affinity to Dirt

Moissanite is by far more resistant to dirt than CZ. All kinds of dirt, cosmetics, oils, powders, etc. will stick to CZ's surface more easily, resulting in a significant loss of luster. While Moissanite will accumulate dirt with time, it will be at a much slower rate than CZ. Just a little bit of dirt will make your cubic zirconia look dull, so you would have to clean it more often when compared to moissanite gemstones.

Price

When it comes to comparing prices, you should know that here we are able to give only general guidance. The actual prices depend on a number of factors, including design, use of other complementary stones and precious metals in the process of jewelry manufacturing, etc.. As a general rule, diamonds are understandably on the top, followed by moissanite diamonds, whereas cubic zirconia can be so inexpensive that they are readily used in costume jewelry production.

Metaphysical Properties

The metaphysical properties of diamond and its spiritual significance and symbolism are generally well known. What about Moissanite and CZ? As artificial stones, their metaphysical power is diminished, especially if compared to natural diamonds. But you should take into consideration that even natural diamonds are often artificially enhanced. There are also some rare finds of natural moissanite, however that's not even close a gem quality material.

Video Comparison with Diamond and Synthetic White Sapphire

Check the video below to compare the look of similar size standard cubic zirconia ($3-$6 per carat), lab-grown white sapphire ($240+ per carat), lab-grown Moissanite ($400+ per carat), and D color internally flawless ideal cut 1.12 carat genuine diamond ($50,000+ per carat).

Outlook

At the end, let us summarize. Are you in a dilemma what to choose: Moissanite or CZ? Choose moissanite by all means. Provided that you can afford the more expensive moissanite, we cannot actually think of a situation where cubic zirconia would be a better choice.

About the Author

The author is a blogger and owner of moissanitediamonds.net.

Comments:

Cici says:
11-22-2015

this was great information! thanks

Jello says:
04-14-2016

Moissanite is basically silicon carbide, which as far as I know is used as an abrasive and is relatively common. How come it is so expensive?

sunnyray says:
04-14-2016

The abrasive silicon carbide is in a form of polycrystalline powder and as such relatively inexpensive. Moissanite is a sizeable single crystal, and as such very veru difficult to make and thus very expensive. Charles & Colvard hold the patent for moissanite production.

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