Moissanite, a brilliant material often selected for fine jewelry, is known for its intense sparkle and high durability. The material’s history and origin are complex, involving both extraterrestrial discovery and sophisticated laboratory engineering. The stones used in commerce today are almost exclusively grown in controlled environments due to the extreme scarcity of naturally occurring deposits.
The Extraterrestrial Origin of Natural Moissanite
The story of natural moissanite begins in a celestial impact zone, not a terrestrial mine. French chemist Henri Moissan discovered the mineral in 1893 while examining rock samples from the Canyon Diablo meteorite crater in Arizona. The microscopic crystals he found were initially mistaken for diamonds, but further analysis revealed a unique composition: silicon carbide.
The silicon carbide grains are commonly found around carbon-rich stars and preserved within primitive meteorites, such as carbonaceous chondrites, indicating they formed outside of our solar system. On Earth, natural moissanite is exceedingly rare, found only in minute quantities within certain corundum deposits and deep-earth formations like kimberlite pipes, which are also sources of diamonds.
The crystals found in these natural deposits are typically too small and contain too many imperfections to be cut into usable gemstones for jewelry. For nearly a century after its discovery, natural moissanite remained a scientific curiosity rather than a commercial material. This rarity is the primary reason why virtually all moissanite used in the modern jewelry market is produced synthetically.
Silicon Carbide: The Chemical Identity
Moissanite is silicon carbide, or SiC, a compound made of silicon and carbon atoms. This composition is fundamentally different from diamond, which is made entirely of pure carbon. In moissanite’s crystal structure, each carbon atom is bonded to four silicon atoms in a tetrahedral arrangement, creating a strong covalent network.
It is exceptionally hard, measuring approximately 9.25 to 9.5 on the Mohs scale, which is second only to diamond’s 10. This chemical arrangement also results in a high refractive index, which is responsible for the material’s remarkable brilliance and fire.
How Commercial Moissanite is Synthesized
Scientists replicate the high-temperature, high-pressure conditions that allow silicon carbide to form in nature. The most common and successful method for growing gem-quality crystals is the Physical Vapor Transport (PVT) process.
This synthesis begins with high-purity silicon carbide powder placed inside a specialized graphite crucible. The crucible is heated to intensely high temperatures, often exceeding 2,500°C, in an inert atmosphere, causing the silicon carbide to sublime, meaning it turns directly into a gas without passing through a liquid state. The resulting SiC vapor is then transported and allowed to condense onto a cooler, pre-existing moissanite seed crystal.
The process requires extremely precise control over temperature gradients and atmospheric pressure to ensure the consistent, slow growth of large, single crystals. This meticulous growth phase can take several months. The controlled environment of the laboratory allows manufacturers to produce colorless, inclusion-free crystals that are chemically and structurally identical to natural moissanite, but in sizes suitable for cutting into brilliant gemstones.