Moissanite, a brilliant gemstone, is recognized for its exceptional sparkle and durability. Chemically, it is silicon carbide (SiC), a compound formed from silicon and carbon atoms. Its origins are unique, encompassing both extremely rare natural occurrences and a sophisticated lab-grown creation process. This duality makes moissanite a fascinating subject.
The Rare Natural Occurrence
The story of moissanite began in 1893 with French chemist Henri Moissan. He discovered tiny, sparkling crystals while examining rock samples from a meteor crater near Canyon Diablo, Arizona. Initially, he misidentified these crystals as diamonds. However, further analysis in 1904 revealed they were naturally occurring silicon carbide. This new mineral was named moissanite in his honor.
Natural moissanite is exceptionally rare on Earth, primarily found in minuscule quantities within meteorites, such as the Canyon Diablo meteorite. Its presence in these extraterrestrial fragments confirms its cosmic origin. Beyond meteorites, it has also been found in trace amounts as inclusions in some terrestrial rocks, but these occurrences are equally uncommon and yield crystals too small for jewelry.
Cultivating Moissanite in the Lab
Given the extreme rarity of natural moissanite, virtually all moissanite on the market today is lab-created. This cultivation makes the durable and brilliant gemstone accessible and affordable, serving as an appealing alternative to traditional gemstones.
Lab creation ensures a consistent supply of moissanite gemstones with uniform quality and sizes suitable for jewelry. This controlled environment ensures each crystal meets specific standards for clarity and brilliance. Cultivating moissanite in a laboratory has shifted its primary source from a rare cosmic mineral to a product of scientific manufacturing.
The Science Behind Lab Creation
Creating moissanite in a laboratory involves growing silicon carbide (SiC) crystals through highly controlled processes. The most widely used technique is a seeded sublimation process, also known as the Lely method or Physical Vapor Transport (PVT). This method begins by placing a small, high-quality silicon carbide seed crystal within a specialized graphite crucible.
Silicon carbide powder is then heated to extremely high temperatures, typically ranging from 2500°C to 2730°C. At these temperatures, the silicon carbide sublimes, turning directly from a solid into a vapor. This vapor then redeposits onto the cooler seed crystal, allowing a larger moissanite crystal to grow layer by layer. Precise control over conditions like temperature gradients, atmospheric pressure, and the purity of raw materials is crucial for successful crystal formation and to influence the gemstone’s final properties. The entire growth process can be slow, with a single crystal sometimes taking up to two months to fully form.