Moissanite costs 1/10th the price of diamonds and sparkles brighter because of its higher refractive index. The occurrence of moissanite (silicon carbide) in nature is very rare, but it can now be manufactured in factories to be used as an imitation for diamonds.

Other than price, a big difference between diamonds and moissanite is that diamond is a great electric insulator, while moissanite is an electric conductor.

Comparison chart

Diamond versus Moissanite comparison chart
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Color Diamonds usually have a yellow or brown tinge, the truly colorless diamonds are very rare. Transparent, green, yellow
Luster Adamantine Adamantine to metallic
Definition Diamond is a natural mineral, an allotrope of carbon. Moissanite is a rarely occuring natural mineral, but can also be synthesized in the laboratory (silicon carbide) as a diamond simulant.
Occurence Natural. Natural and factory-made. Typically inclusions in diamonds, xenoliths, ultramafic rocks – kimberlite, lamproite Carbonaceous chrondite meteorites.
Refractive Index 2.417 nω=2.654 nε=2.967, Birefringence 0.313 (6H form)
Cost High Not very expensive. One-tenth of a diamond.
Crystal system Hexoctahedral (cubic) Most common: 6H hexagonal (6mm), space group: P63mc
Hardness Extremely hard (10 on Mohs scale). The hardest known natural material. Very hard. 9.5 on Mohs scale.
Crystal habit Isometric, Octahedral Hexagonal
Use Jewelry; industrial purposes – high-pressure experiments, cutting tools. Jewelry, most often as diamond simulant. High-pressure experiments, replacing diamonds
Specific gravity Diamond has a specific gravity of 3.52 3.218–3.22
Dispersion 0.044 (lower than cubic zirconium and moissante) 0.104
Thermal conductivity Diamonds are among the most efficient thermal conductors Good thermal conductivity, comparable to diamond.
Electric Conductivity Bad; diamond is an electric insulator. Very good electric conductor.
Melting Point 3550 C (6422 F) 2730 °C (decomposes)
Chemical formula C SiC
Material Natural Natural, synthetic

What is Moissanite?

Moissanite is a rare, naturally-occurring mineral with various crystalline polymorphs, although it is now possible to manufacture moissanite in factories, making it ten times less expensive than diamond. Moissanite has a high refractive index and is hence much more brilliant as well as iridescent as compared to a diamond.

Appearance

Typical diamond colors include yellow, brown, gray and no-color. Less typical colors include blue, green, black, translucent white, pink, violet, orange, purple and red.

Typical colors include transparent, green and yellow. Moissanite is often found as an inclusion in diamonds, xenoliths and ultramafic rocks such as kimberlite and lamproite. It is often an inclusion in carbonaceous chrondite meteorites as well.

How to Identify Diamond from Moissanite

While experienced jewelers may be able to tell the difference between diamond and moissanite, there are tester tools designed specially to tell the two apart is available in the market. Moissanite has a higher refractive index and dispersion; it is more brilliant and iridescent than a diamond. In fact, the bigger the moissanite, the easier it becomes to identify it as it tends to lose its hue. Another test is that moissante is a conductor of electricity while diamond is an insulator.

More on diamond and moissanite:

Properties

The properties of diamond and moissanite are quite similar - more similar than those of cubic zirconia. The chemical formula is for diamond is C, while that of moissanite is SiC.

Brilliance

Both diamond and moissanite disperse light very well, which creates the sparkle. Diamond's refractive index of 2.418 is lower than moissanite's 2.654 to 2.967, which makes moissanite more resplendent, even flashy according to some. In the 6H form, moissanite's refractive index is 0.313. Dispersion in diamond is 0.044, lower than moissanite's 0.104. Between the refractive index and dispersion rate, moissanite tends to show more brilliantly and with a little more fire than diamond.

Both diamond and moissanite have an adamantine luster, though moissanite's can range to metallic.

Hardness

Diamond is the hardest known substance. It scores a 10 on the Mohs scale. It is a good abrasive and can be scratched only by other diamonds. Because of this property, a diamond is used to polish, cut, or wear away any material, including other diamonds.

Moissanite is nearly as hard, scoring 9.5 on the Mohs scale.

Crystal

Diamond is an isometric crystal from the isometric-hexoctahedral crystal system, or categorization of crystal types. Its crystal habit is octahedral, meaning diamonds typically form in this shape.

Moissanite is a hexagonal crystal most commonly found in the 6H hexagonal crystal system. However, it also belongs to the space group P63mc, which is a description of crystal symmetry. The moissanite crystal habit is as an inclusion in other minerals.

Electrical and Thermal Conductivity

Diamonds are electric insulators and excellent thermal conductors. The thermal conductivity of moissanite is comparable to that of diamond, but unlike diamond, moissanite is an electric conductor. This test is often used to tell the two apart.

Cost

Diamonds cost about ten times more than moissanite. Gem-grade diamonds are used in high-end jewelry. Rough diamonds must first be cut and polished before they are sold as gemstones, either already set in jewelry or loose.

Alternatives

Like moissanite, diamonds can be created in a lab. However, unlike diamond simulants like moissanite, cubic zirconia, white sapphire and yag, lab-created (aka synthetic) diamonds are indistinguishable in appearance and properties from a natural diamond. Lab-created diamonds, although cheaper than natural mined diamonds, cost much more than moissanite and other simulants.

Many manufacturers of lab-created diamonds are now moving away from the term "synthetic diamond," as they do not want consumers to confuse lab-created diamonds with "fake diamonds" or simulants mentioned above.

The video below gives detailed information on the types of diamonds and its simulants regarding their price, pros and cons:

Other Applications

Because of its hardness and thermal conductivity, diamond is also used in industrial processes. Most industrial-grade diamond comes as a by-product of the cutting and polishing process for gemstones. Industrial-grade diamond is often used in high-pressure experiments and in cutting tools.

Moissanite is also used for jewelry, often as a simulation of diamonds. Apart from jewelry, moissanite is often used to replace diamonds in high-pressure experiments. Since natural moissanite is so rare, the created form of the mineral is usually used for both purposes. The cost of moissanite is approximately 1/10th that of diamond.

Natural History

Diamonds have been known in India for millennia, having been treasured in their use in religious icons. Diamonds are formed when carbon is exposed to high pressure at a comparatively low temperature range. They are only found in the lithospheric mantle below stable continental plates and at the site of meteor strikes. Moissanite is named after French chemist Henri Moissan, who discovered the rare mineral in a meteor crater. Moissanite occurs as an inclusion in other minerals. It is found only in the upper mantle rock of the earth and at the site of a meteor strike.

References

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