Moissanite is one of the most scientifically fascinating gemstones used in jewelry — and understanding what it's made of helps explain why it performs so exceptionally. Here's the complete science, explained clearly.
The Chemical Composition: Silicon Carbide
Moissanite is silicon carbide (SiC) — a compound of silicon and carbon atoms arranged in a crystal lattice structure. Its chemical formula is SiC. This is the same material used in industrial applications like bulletproof vests, high-performance brake discs, and semiconductor electronics — which gives you an immediate sense of its exceptional hardness and thermal stability.
Diamond, by comparison, is pure carbon (C). Moissanite is not a form of diamond — it is a completely different material with different chemistry, different crystal structure, and different optical properties. It is not a diamond simulant in the sense of being an inferior copy; it is a distinct gemstone with its own exceptional properties.
Natural vs. Lab-Created Moissanite
Natural moissanite was first discovered in 1893 by French chemist Henri Moissan in a meteorite crater in Canyon Diablo, Arizona. He initially believed he had found diamonds, but later identified the crystals as silicon carbide — a material previously unknown in nature. Natural moissanite is extraordinarily rare — it exists in tiny quantities in meteorites and some geological formations, but never in gem-quality sizes suitable for jewelry. Read more: The Story of Henri Moissan.
Lab-created moissanite is produced through a controlled thermal growth process. Silicon and carbon are combined under high temperature and pressure conditions that replicate the extreme environment in which natural silicon carbide forms. The result is a single-crystal silicon carbide gemstone that is chemically and physically identical to natural moissanite — but produced in gem-quality sizes and quantities suitable for jewelry. Read more: How Is Moissanite Made?
Why Silicon Carbide Makes an Exceptional Gemstone
Hardness: Silicon carbide scores 9.25 on the Mohs hardness scale — the second hardest gemstone material used in jewelry after diamond (10). This hardness comes from the strong covalent bonds between silicon and carbon atoms in the crystal lattice. It will not scratch from contact with any material softer than 9.25 — which includes virtually everything you encounter in daily life. Read more: Moissanite Mohs Hardness: The Science Explained.
Thermal stability: Silicon carbide is one of the most thermally stable materials known. It begins to oxidize only above approximately 1,000°C (1,832°F) — far beyond any temperature encountered in daily life or jewelry manufacturing. This is why moissanite can be safely worked with a jeweler's torch during resizing or repair. Read more: Moissanite in Hot Weather or Extreme Heat.
Optical properties: Silicon carbide is doubly refractive — light entering the crystal splits into two rays, each traveling at a different speed. This produces moissanite's characteristic exceptional brilliance and fire. Its refractive index (2.65–2.69) is higher than diamond's (2.42), and its dispersion rate (0.104) is more than double diamond's (0.044). Read more: Does Moissanite Sparkle More Than Diamond?
Chemical inertness: Silicon carbide does not react with acids, bases, or oxidizing agents under normal conditions. It will not tarnish, discolor, or degrade from exposure to skin oils, cleaning products, pool chemicals, or salt water. Read more: Does Moissanite Tarnish?
GRA Certification
Every moissanite stone sold by Moissanite Shine is certified by the Gemological Research Association (GRA), which verifies the stone's composition, color grade, clarity grade, and carat weight. Read more: GRA Certificate Explained.
Explore our engagement ring collection — all DEF color, VVS1 clarity, GRA-certified silicon carbide moissanite.
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Related guides:
How Is Moissanite Made?
The Story of Henri Moissan
Moissanite Mohs Hardness: The Science
Does Moissanite Sparkle More Than Diamond?
Is Moissanite a Real Gemstone?