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Education
The word Diamond comes from the Greek word Adamas, which means
indestructible. It is the only gem known to man that is made of a single
element, Carbon, besides graphite. Diamond is completely made of
Carbon atoms (Chemical Composition - C) crystallized in a cubic
(isometric) arrangement.
Diamonds form between 120-200 kilometers or 75-120 miles below the
earth's surface. According to geologists the first delivery of diamonds was
somewhere around 2.5 billion years ago and the most recent was 45
million years ago. According to science, the carbon that makes diamonds
comes from the melting of pre-existing rocks in the Earth's upper mantle.
There is an abundance of carbon atoms in the mantle.
Temperature changes in the upper mantle forces the carbon atoms to go
deeper where it melts and finally becomes new rock, when the
temperature reduces. If other conditions like pressure and chemistry are
right then the carbon atoms in the melting crystal rock bond to build
diamond crystals.
There is no guarantee that these carbon atoms will turn into diamonds. If
the temperature rises or the pressure drops then the diamond crystals may
melt partially or totally dissolve. Even if they do form, it takes thousands of
years for those diamonds to come anywhere near the surface.
How do diamonds get to the surface?
Diamonds ascend to the Earth's surface in rare molten rock, or magma
that originates at great depths. Carrying diamonds and other samples from
Earth's mantle, this magma rises and erupts in small but violent volcanoes.
Just beneath such volcanoes is a carrot-shaped "pipe" filled with volcanic
rock, mantle fragments, and some embedded diamonds. The rock is called
kimberlite after the city of Kimberley, South Africa, where the pipes were
first discovered in the 1870s. Another rock that provides diamonds is
lamproite.
The volcano that carries diamond to the surface emanates from deep
cracks and fissures called dikes. It develops its carrot shape near the
surface, when gases separate from the magma, perhaps accompanied by
the boiling of ground water, and a violent supersonic eruption follows. The
volcanic cone formed above the kimberlite pipe is very small in
comparison with volcanoes like Mount St. Helens, but the magma
originates at depths at least 3 times as great. These deep roots enable
kimberlite to tap the source of diamonds. Magmas are the elevators that
bring diamonds to Earth's surface.
The search for diamonds has determined that most are derived from
kimberlite pipes in the oldest, nuclear portions of the continents, where the
basement rocks are older than 1.5 billion years. The oldest parts of
continents are called cratons, and can be divided into two terranes:
Archean-age archons, which are older than 2,500 million years, and
Proterozoic-age protons, which are 1,600 -- 2,500 million years old. The
distribution of these terranes is shown on the map.
The complex volcanic magmas that solidify into kimberlite and lamproite
are not the source of diamonds, only the elevators that bring them with
other minerals and mantle rocks to Earth's surface. Although rising from
much greater depths than other magmas, these pipes and volcanic cones
are relatively small and rare, but they erupt in extraordinary supersonic
explosions
Today diamonds are mined in about 25 countries, on every continent but
Europe and Antarctica. However, only a few diamond deposits were
known until the 20th century, when scientific understanding and technology
extended diamond exploration and mining around the globe. For 1,000
years, starting in roughly the 4th century BC, India was the only source of
diamonds. In 1725, important sources were discovered in Brazil, and in
the 1870s major finds in South Africa marked a dramatic increase in the
diamond supply. Additional major producers now include several African
countries, Siberian Russia, and Australia.
Artificial Diamonds
Artificial diamond is diamond produced through chemical or physical
processes in a laboratory. Like naturally occurring diamond it is composed of
a three-dimensional carbon crystal. Artificial diamonds are also called
cultured diamonds, manufactured diamonds, and synthetic diamonds.
History
Artificial diamonds were first produced on February 16, 1953 in Stockholm,
Sweden by the QUINTUS project of ASEA, Sweden's major electrical
manufacturing company using a bulky apparatus designed by Baltzar von
Platen. Pressure was maintained within the device at an estimated 83,000
atmospheres for an hour. A few small crystals were produced. The discovery
was kept secret.
Nevertheless, General Electric researchers reported their own successful
diamond synthesis in Nature. The production of smaller artificial diamonds
and especially diamond dust has become an important industry with General
Electric at the forefront. General Electric, along with Sumitomo Electric and
De Beers marketed their synthetic stones as heat sinks for electronics and
used them solely for research purposes. Significantly, the majority of these
artificial diamonds are not of gem quality.
Moissanite: Simulated Diamond
Fifty thousand years ago, long after this creature had vanished, a meteorite
crashed into the Arizona desert creating what is now known as "Meteor
Crater." Fragments of this meteorite were scattered across the desert.
Hidden in these fragments was a brilliant secret waiting to be discovered.
In 1893, Nobel-Prize winning scientist Henri Moissan began studying
fragments of this meteorite in nearby Diablo Canyon. In these fragments Dr.
Moissan discovered minute quantities of a shimmering new mineral, with fire
and brilliance never before seen on earth. After extensive research, Dr.
Moissan concluded that this mineral was made of silicon carbide.
Detecting Moissanite
(For more information: http://www.moissanite.com/)
Testers: Since Moissanite tests positive on a standard electronic Diamond
Tester, a special Moissanite Testers can be used to identify Moissanite
Conventional diamond testers test for thermal conductivity and are useful in
separating diamond from simulants such as cubic zirconia, corundum, glass,
synthetic rutile, and zircon. Thermal diamond testers cannot be used to
discriminate diamond from moissanite, because both are thermally
conductive.
An electrical conductivity tester, designed specifically for testing Moissanite,
will indicate Moissanite and would ideally be used after a thermal diamond
tester has eliminated other simulants.
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