Moissanite vs CZ

Moissanite is a unique gemstone with its own distinct properties and characteristics that set it apart from other diamond alternatives. While it may resemble diamond at first glance, it has a higher refractive index and dispersion, giving it more fire and brilliance than diamond. Moissanite is not a synthetic diamond but a naturally occurring mineral that is grown in a laboratory environment.

In contrast, cubic zirconia (CZ) is a synthetic material that is manufactured to look like a diamond. CZ is often marketed as a cheap alternative to diamond and is mass-produced under various brand names. However, CZ is generally considered to be of lower quality than Moissanite, with lower hardness and durability, and less brilliance and fire.

It is important to note that Moissanite is not a diamond simulant, but a gemstone in its own right with its own unique properties and beauty. While it may resemble diamond to the untrained eye, it is important to understand the differences between Moissanite, CZ, and other diamond alternatives before making a purchase. Please refer to the next section: Commonly Marketed Gemstones & Diamond Alternatives.

CZ is too soft

Scratched Gemstone

Hardness is the resistance of a gemstone to being scratched or the facets being worn down. Compared to Moissanite, CZ has less than one half (45%) the hardness of Moissanite as measured using the Knoop indention test: 1370 kg/mm2 vs. 3000 kg/mm2. Therefore, Moissanite is 219% harder. Because CZ scratches easily, it can lose its surface luster after just a few months or years with regular wear.

Although CZ sellers boast that CZ can scratch glass, many gemstones and jewels are ranked above glass in hardness and can easily scratch it as well. Therefore this is no amazing feat.

CZ is not tough enough

Chipped Gemstone

When it comes to toughness, which refers to a gemstone's resistance to chipping and breaking, CZ is significantly less tough than Moissanite. In fact, CZ has only one-third the toughness of Moissanite, with a measurement of 2.4 PSI compared to Moissanite's 7.6 PSI. This means that Moissanite is over 300% more resistant to chipping than CZ.

On the other hand, Moissanite's high hardness and toughness make it much more durable than CZ, which has a finite life due to its lower properties. While CZ can easily scratch, chip, and wear with regular use, Moissanite can withstand everyday wear and last a lifetime and beyond with proper care.

CZ has inferior optical properties

Sparkle Gemstone

The allure and radiance of engagement gemstones are attributed to their brilliance, fire, and luster.

Moissanite boasts a remarkable refractive index of 2.69, which is 25% higher than that of CZ. A gemstone's refractive index correlates with its ability to reflect light, making Moissanite more brilliant than CZ.

Moissanite also exhibits a dispersion of 0.104, which is 58% greater than that of CZ (0.044). This feature causes Moissanite to emit more rainbow-colored light, or fire, compared to CZ.

Furthermore, Moissanite's luster is 50% greater than CZ's. The luster of a gemstone is determined by its capacity to reflect light from its surface, making Moissanite more lustrous than CZ.

In conclusion, Moissanite has significantly higher levels of brilliance, fire, and luster than CZ.

Optical Anamolies: Windowing


The lower refractive index of CZ causes the stone to exhibit substantially more "windowing" than a Moissanite or diamond and gives CZ what many women refer to as a "glassy" appearance.

Windowing is an optical phenomenon that occurs when light passes through a gemstone without being refracted. If windowing is present in a gemstone the observer can look through the stone at certain angles as if it were a window or can observe large dark areas in the stone (caused by light leaking out the window).

A well-cut stone should reflect so much light that nothing is seen behind it. However, this statement presumes that you are looking straight down through the top of the stone, and the stone is not tilted at all. Tilting the stone even slightly will change the angles of light hitting the pavilion facets. Each type of gem has its own range of "tilt brilliance". The lower the refractive index the less tilting it takes to window the stone. Since the refractive index of CZ is substantially lower than Moissanite (1.8 - 2.17 compared to Moissanites 2.69), the result is that although a CZ may look pretty when viewed from the top, but when viewed at various angles many dark or black spots can appear, making it easy to spot as a "fake".

CZ has Strong Affinity to Dirt

Cubic zirconia (CZ) exhibits a high tendency to attract dirt, making it susceptible to losing its shine and appearing cloudy, according to the opinions of many consumers. This is largely due to the gemstone's propensity to accumulate hand oils, cosmetics, and other substances quickly. The CZ's inferior refractive index relative to that of a diamond or moissanite makes it particularly vulnerable to dullness or lifelessness even from slight accumulations of dirt. Consequently, frequent cleaning is necessary to maintain its sparkle, sometimes even multiple times a day, as reported by some customers. In contrast, although moissanite can become soiled over time, it is more resistant to dirt than CZ and even diamonds, allowing it to remain clean and sparkling for a longer duration.

CZ lacks stability and durability

Burning Stone

Cubic zirconia (CZ) is susceptible to heat damage. Excessive exposure to heat can cause the CZ stones to break and turn an opaque, milky color, which can pose a challenge if you intend to alter your CZ jewelry, such as resizing a ring. Many jewelers may decline to offer repair services for CZ jewelry due to this issue.

Moreover, CZ stones exhibit a natural tendency to bond with metals, which can lead to challenges in jewelry repair or modification.


Ultimately, CZ is an excellent option for creating affordable fashion jewelry. However, if you plan to wear the jewelry frequently, such as for bridal purposes, CZ may not be the most suitable choice due to its softness and vulnerability to damage. In addition, CZ has a high affinity for dirt, and its optical properties, including luster, fire, and brilliance, are inferior to those of Moissanite. Unlike Moissanite and diamond, CZ may not withstand the test of time, which could be a crucial factor when selecting a gemstone for long-term use.

Toughness Moissanite is 317% more tough
R.I. (Brilliance) Moissanite is 25% more brilliant
Fire (dispersion) Moissanite has 58% more fire
Luster Moissanite has 50% more luster
Windowing CZ demonstrates obvious windowing, giving it a glass-like appearance. Moissanite displays less windowing than even diamond.
Affinity to Dirt: Moissanite requires substantially less cleaning
Durability Unlike CZ, Moissanite will not shatter when jeweler applies heat
Stability: Unlike CZ, will not react with CO2 and water