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| Home � Daimond Advice � Diamond from Mine to Market |
| Diamond from Mine to Market |
What is a Diamond? |
A diamond is a crystal made up entirely of
carbon atoms that are arranged in an isometric, or cubic, matrix. A cubic
crystal arrangement is one in which the crystal essentially expands outward at
the same rate in all directions during its initial growth; the ideal result,
when the crystal forms without any interference, is a pure and perfectly formed
octahedral shape.
However, most diamond crystals encounter varying heat
or pressure, other elements, or even other diamond crystals during their growth,
and this can alter their form somewhat. The resulting form and characteristics
of the crystal, once it emerges from the earth, help to determine what shape,
color and clarity the polished gem will have.
The combination of
diamond's molecular composition and its crystal structure is what makes it so
unique and gives it all the qualities that we think of when we think of a
diamond.
Consider this: The graphite that you commonly find in pencils
is also made of pure carbon, but because the carbon atoms are arranged
differently, the result is a soft gray-black substance that is very unlike hard,
colorless diamond. And iron pyrite (known more commonly as "fool's gold") grows
in an isometric arrangement, but because it is not made of pure carbon, it also
lacks the spectacular qualities of diamond.
The unique characteristics
of diamond go far beyond what you can see with your eye. In addition to their
superior brilliance and dispersion, diamonds are the hardest natural substance
on earth.
Diamond rates a 10 on the Mohs scale of hardness, which means
that it is extremely resistant to scratches; it is several times harder than the
next-hardest substance, corundum, which is more commonly known as ruby and
sapphire.
Diamonds are also very tough, meaning that they do not easily
break, chip or crack. And even more interestingly, they are extremely resistant
to heat and chemicals: it would take a temperature of at least 720� Celsius in
air, or 850� Celsius in a vacuum, to burn a diamond; and sulphuric and
hydrochloric acids, which are capable of completely dissolving the skin and
bones of a person, have no effect at all on diamonds (in fact, these acids are
actually used to clean the oil and dust off polished diamonds after they have
been cut).
Where does a diamond come from?
Diamond is formed when carbon atoms deep in the earth are exposed
to enormous heat and pressure over millions of years. In fact, the first known
diamond deposits were brought to the surface of the earth two and a half billion
years ago, and the most recent deposits are 50 million years, meaning that all
diamonds are a genuine piece of pre-history!
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Diamonds made their journey from the asthenosphere (the
layer of earth that lies 75 to 125 miles below the crust) to the surface when
volcanic activity forced them, along with other rocks and minerals such as
kimberlite, upward in a powerful explosion that formed a 'pipe' (a deep, wide
opening in the earth).
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Once the diamonds and rocks shot upward, most of them
fell back and settled into the pipes; when these pipes were eventually
discovered by miners, they became known as 'primary deposits' of diamond. Other
diamonds, though, were washed away either by erosion or by nearby waters; these
formed deposits a distance away from the original source and they became known
as 'alluvial deposits.'
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The first known source of diamonds was India, but now
it is the countries of Australia, Botswana, Namibia, South Africa, Russia and
Canada which produce as much as 80% of the world's diamonds.
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| Diamonds are not at all easy to mine. In fact, more
than 250 tons of ore need to be blasted, crushed and processed to yield just one
carat of rough diamond! And of all the diamonds mined, only about 20% to 25% are
gem-quality; the rest will eventually be used for technological and industrial
purposes, or as abrasives. |
How does a diamond get from the mines to the stores?
Finding the rough diamonds is only the first step. Once diamonds have been mined and
processed out of the 'overburden' (that is, the kimberlite rocks in which they
are imbedded), the rough crystals are sorted and categorized according to their
size, color, shape and other characteristics. At this point, a diamond can
follow one of two routes:
The most common route is through the channels of DeBeers' Central
Selling Organization (CSO). Many people are familiar with DeBeers mainly because
of their advertisements and commercials and because of the famous motto that
they coined in the early half of the 20th century: "A Diamond is Forever."
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While DeBeers' market influence has decreased somewhat over the
last few years, they still control the majority of the world's diamond
production (an estimated 30% to 40% of annual diamond production). The
purchasing arm of the CSO not only buys diamonds from member mines around the
world; it also finances mining technology for governments which do not have the
means to mine their own deposits. Most of what is bought through the CSO is sent
to London to be offered to buyers through DeBeers marketing arm, the Diamond
Trading Corporation (DTC).
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The DTC holds ten week-long selling sessions called 'sights' each
year. These sights are by invitation only, and only a handful of diamond
manufacturers from around the world (called 'sightholders') are allowed to
attend. These sightholders may chose to cut the rough diamonds they buy
themselves, or they may chose to sell some of the rough diamonds to smaller
manufacturers.
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These smaller manufacturers cut the rough diamonds and sell the
polished gems either to jewelry manufacturers (who set the diamonds into
finished pieces of jewelry and then sell the jewelry to jewelry retailers), or
to diamond wholesalers (who then, in turn, sell the diamonds to diamond
retailers).
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| In the less common route from mine to market, some independent
miners elect not to sell their mine production to the DeBeers cartel. Instead,
they offer newly mined diamonds directly to other world buyers. These buyers, in
turn, may chose to cut and sell the diamonds themselves, or pass the diamonds
along within the industry in a manner similar to that described
above. |
How is a diamond cut?
A newly mined rough diamond looks more like a piece of glass
washed up on the beach than like the polished gems sold in jewelry stores.
Bringing out their beauty requires the skill and art of a trained diamond
cutter.
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While incredibly precise, computerized machinery is now used in
some parts of the cutting process for some diamonds, most of the work is still
performed by hand using exacting and meticulous techniques passed down over the
generations.
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As a first step, cleaving or sawing is often used to separate the
original rough into smaller, more workable pieces that will each eventually
become an individual polished gem. Next, bruting grinds away the edges,
providing the outline shape (for example, heart, oval or round) for the gem.
Faceting is then done in two steps: during blocking, the table, culet, bezel and
pavilion main facets are cut; afterward, the star, upper girdle and lower girdle
facets are added.
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Once the fully faceted diamond has been inspected and
improved, it is boiled in hydrochloric and sulfuric acids to remove dust and
oil. The diamond is then considered a finished, polished gem.
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