Moissanite (/ˈmɔɪsənaɪt/)[4] is the name given to naturally occurring silicon carbide and to its various crystalline polymorphs. It has the chemical formula SiC and is a rare mineral, discovered by the French chemist Henri Moissan in 1893. Silicon carbide is useful for commercial and industrial applications due to its hardness, optical properties and thermal conductivity. Efforts to synthesize silicon carbide in a laboratory began in the late 1800s.
Moissanite was introduced to the jewelry market in 1998 after Charles & Colvard, formerly known as C3 Inc., received patents to create and market lab-grown silicon carbide gemstones, becoming the first firm to do so. Charles & Colvard currently makes and distributes moissanite jewelry and loose gems under the trademarks Forever One, Forever Brilliant and Forever Classic.[16] Other manufacturers market silicon carbide gemstones under trademarked names such as Amora and Berzelian. Moissanite is regarded as a diamond alternative, with some optical properties exceeding those of diamond. Its lower price and less exploitative mining practices necessary to obtain it make it a popular alternative to diamonds. Due in part to the similar thermal conductivity of moissanite and diamond, it is a popular target for scams; however, higher electrical conductivity and birefringence of moissanite may alert a buyer to fraud. In addition, thermoluminescence is exhibited in moissanite, such that heating it gradually will cause it to change color starting at around 65 °C (150 °F). This color change can be diagnostic for distinguishing diamond from moissanite, although birefringence and electrical conductivity differential are more practical diagnostic differentiators.[17] On the Mohs scale of mineral hardness it is a 9.5, with a diamond being a 10.[3] In many developed countries, the use of moissanite in jewelry was controlled by the patents held by Charles & Colvard; these patents expired in August 2015 for the United States, and will expire in 2016 in most other countries except Mexico, where it will remain under patent until 2018.[18][19][20]
Because of its hardness, it can be used in high-pressure experiments, as a replacement for diamond (see diamond anvil cell).[5] Since large diamonds are usually too expensive to be used as anvils, synthetic moissanite is more often used in large-volume experiments. Synthetic moissanite is also interesting for electronic and thermal applications because its thermal conductivity is similar to that of diamonds.[14] High power silicon carbide electronic devices are expected to find use in the design of protection circuits used for motors, actuators, and energy storage or pulse power systems.[21]
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