Moissanite, a diamond simulant, burst onto the jewelry scene in the late 1990s, creating quite a turmoil. Composed of silicon carbide (SiC), the gem quality mineral, unlike other diamond simulants, is also a thermal conductor. Diamonds are known for their thermal conductivity, and it is that characteristic that is used as a test for authenticity. So, moissanite, which looked like a fake diamond, but passed the thermal conductivity test, confused jewelers around the world.
Moissanite was originally discovered in 1893, in Arizona, by Nobel Prize winner Dr. Ferdinand Henri Moissan. In Diablo Canyon, site of a crater formed by a huge meteorite that struck the earth forty thousand years ago, Dr. Moissan discovered bits of what looked like tiny diamonds. In 1905, these “tiny diamonds” were analyzed as silicon carbide, which was named moissanite in honor of Dr. Moissan.
Natural moissanite is rare and virtually unavailable today, so most is man-made. The simplest process is to combine silica sand and carbon at between 1,600 and 2,500 degrees centigrade. In 1893, Edward Goodrich Acheson developed the electric batch furnace, in which SiC is still made today, to produce the silicon carbide. It is believed he was trying to dissolve carbon in molten corundum (alumina). During the process he discovered the presence of blue-black crystals, that he thought was a compound of carbon and corundum, hence the name carborundum.
Today, moissanite information lives in the laboratories of scientists experimenting on silicon carbide, Acheson’s carborundum. Those blue-back crystals were actually less pure, formed father from the heat source and doped with iron or alumina, empowering them with electrical conductivity. Currently, carborundum is used in electrical components, semi-conductors, as abrasives and extremely hard saws.
The SiC crystals formed closer to the heat source, the most pure, are clear, pale yellow and green. These higher purity crystals, with their hardness and amazing luster, are what’s used to create today’s alternative to diamonds.
In 1998, Charles & Colvard introduced gem-quality moissanite, targeting primarily self-purchasing women. Among value-conscious consumers, however, moissanite engagement rings, eternity bands and circle pendants have become popular as well. For good reason: a 1-carat (200 mg) moissanite gem sells for about $500. A diamond of comparable size and color would typically sell for $4500 and up.
Cost, however, is not the only factor in its worth as a diamond substitute. Moissanite is extremely hard, rating a 9.25 on the Mohr’s hardness scale (diamond is 10.0). Its refractive index (brilliance) is slightly higher than diamond and it possesses twice as much fire (flashes of rainbow colors). Plus, unlike cubic zirconia, moissanite doesn’t cloud over time.
Structurally, moissanite is composed of hexagonal crystals, not isometric (cubic), giving the face of the stone double facet edges instead of diamond’s single facets. Moissanite has no cracks and fissures or natural flaws such as impurities, feathers and inclusions. Tiny, white, ribbon-like structures can be present, which are a result of the moissanite growing process.
As for color, it is impossible to produce a pure white moissanite. The stones have a fluorescence of green, gray or yellow under ultraviolet light. The higher refraction of the stone, though, does help to overcome the perceived color. Cuts with higher brilliance such as round brilliant or cushion cut, have a much “white appearance” than cuts with a lower refractive index, or less brilliance, such as the marquis or pear cut.
Moissanite is currently available only from one source. That, plus the extensive manufacturing process, still makes this diamond simulant quite expensive. Certainly less so than diamonds, as noted above, but relative to other man made diamonds, moissanite still carries a hefty price tag.
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