What is Moissanite?
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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