Moissanite is a gemstone composed of silicon carbide (SiC). The direct answer to whether it is all lab-created is yes; the moissanite available commercially for jewelry is entirely synthetic, or lab-grown. This material is synthesized to create crystals large and pure enough to be cut into gemstones. The market relies exclusively on laboratory production because the natural form is exceedingly rare and cannot be mined in jewelry-grade sizes.
The History of Natural Moissanite
The story of moissanite began with a celestial discovery in 1893 by French chemist Henri Moissan. He was examining rock samples from a massive meteorite crater located in Canyon Diablo, Arizona. Moissan initially misidentified the tiny, brilliant crystals he found as diamonds due to their similar hardness and sparkle.
It was later determined, in 1904, that these crystals were a unique mineral composed of silicon carbide, which was then named moissanite in his honor. Natural moissanite is extremely rare and is typically found only in meteorites, in some corundum deposits, or as microscopic inclusions within certain volcanic rocks. Since it does not occur in commercially viable quantities, the natural material remains a scientific curiosity rather than a source for gemstones.
How Silicon Carbide is Grown in a Lab
The moissanite used in jewelry is grown in specialized laboratories as pure silicon carbide (SiC). This synthesis is necessary because natural deposits cannot supply the gem market. The process involves sophisticated high-temperature techniques to form large, single-crystal boules of the material.
The most common method used to create gem-quality moissanite is a variation of the sublimation technique, often called the Modified Lely method. This process involves heating a silicon carbide powder source, or “charge,” to extremely high temperatures, typically between 2,000°C and 2,700°C, inside a controlled environment. At this temperature, the SiC sublimates, turning directly into a gas without passing through a liquid phase.
The gaseous silicon and carbon atoms then travel to a cooler surface containing a silicon carbide seed crystal. The atoms deposit onto this seed, slowly building up a large, high-purity single crystal over several weeks. Precise control of temperature gradients and pressure ensures the formation of a crystal large and clear enough to be cut into a finished gemstone.
Distinguishing Moissanite from Diamond
Although moissanite is often used as a diamond alternative, it is chemically and optically distinct from carbon-based diamond. These differences allow gemologists to distinguish between the two materials based on specific scientific metrics. The optical properties of moissanite are more pronounced, leading to a different appearance under light.
Moissanite has a significantly higher refractive index, ranging from 2.65 to 2.69, compared to a diamond’s fixed index of 2.42. This higher index means moissanite bends light more intensely, resulting in greater brilliance. Moissanite also exhibits a higher dispersion, rated at 0.104, which is over twice that of diamond’s 0.044. This higher dispersion causes the gemstone to break light into more colorful flashes, often described as a “rainbow effect.”
Another distinguishing factor is its crystal structure, which causes moissanite to display double refraction, or anisotropy. In contrast, diamond is singly refractive, creating a crisp, clear image when viewed through a loupe. While diamond is the hardest known mineral at 10 on the Mohs scale, moissanite rates 9.25, making it highly durable for daily wear.