About Diamond

In mineralogy, Diamond is the allotrope of carbon where the carbon atoms are arranged in an isometric-hexoctahedral
crystal lattice. Its hardness and high dispersion of light make it useful for industrial applications and jewelry
It is the hardest known natural material and the third-hardest known material after aggregated diamond nanorods
and ultrahard fullerite.

Diamonds are specifically renowned as a material with superlative physical qualities; they make excellent abrasives
because they can be scratched only by other diamonds, Borazon, ultrahard fullerite, or aggregated diamond nanorods,
which also means they hold a polish extremely well and retain their lustre. Approximately 130 million carats
(26,000 kg) are mined annually, with a total value of nearly USD $9 billion, and about 100,000 kg (220,000 lb)
are synthesized annually.

The name diamond derives from the ancient Greek adamas (???µ??; "invincible"). They have been treasured as gemstones
since their use as religious icons in ancient India and usage in engraving tools also dates to early human history.
Popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and
polishing techniques, growth in the world economy, and innovative and successful advertising campaigns.
They are commonly judged by the "four Cs": carat, clarity, color, and cut.

Roughly 49% of diamonds originate from central and southern Africa, although significant sources of the mineral have
been discovered in Canada, India, Russia, Brazil, and Australia. They are mined from kimberlite and lamproite volcanic
pipes, which can bring diamond crystals, originating from deep within the Earth where high pressures and temperatures
enable them to form, to the surface. The mining and distribution of natural diamonds are subjects of frequent
controversy such as with concerns over the sale of conflict diamonds (aka blood diamonds) by African paramilitary groups.

Material properties

Diamond is a transparent crystal of tetrahedrally bonded carbon atoms and crystallizes into the face centered cubic
diamond lattice structure. Diamonds have been adapted for many uses because of the material's exceptional physical
characteristics. Most notable are its extreme hardness, its high dispersion index, and extremely high thermal
conductivity (900 - 2320 W/m K), with a melting point of 3820 K (3547 °C / 6420 °F) and a boiling point of 5100 K
(4827 °C / 8720 °F).[5] Naturally occurring diamonds have a density ranging from 3.15 to 3.53 g/cm³, with very pure
diamond typically extremely close to 3.52 g/cm³.

Hardness

Diamond is the hardest natural material known to humankind; hardness is defined as resistance to scratching.
Diamond has a hardness of 10 (hardest) on Mohs scale of mineral hardness.Diamond's hardness has been known
since antiquity, and is the source of its name.

The hardest diamonds in the world are from the New England area in New South Wales, Australia. These diamonds
are generally small, perfect to semiperfect octahedra, and are used to polish other diamonds. Their hardness is
considered to be a product of the crystal growth form, which is single stage growth crystal. Most other diamonds
show more evidence of multiple growth stages, which produce inclusions, flaws, and defect planes in the crystal
lattice, all of which affect their hardness.

The hardness of diamonds contributes to its suitability as a gemstone. Because it can only be scratched by other
diamonds, it maintains its polish extremely well. Unlike many other gems, it is well-suited to daily wear because
of its resistance to scratching-perhaps contributing to its popularity as the preferred gem in an engagement ring
or wedding ring, which are often worn every day.

Industrial use of diamonds has historically been associated with their hardness; this property makes diamond the
ideal material for cutting and grinding tools. As the hardest known naturally-occurring material, diamond can be
used to polish, cut, or wear away any material, including other diamonds. However, diamond is a poor choice for
machining ferrous alloys at high speeds. At the high temperatures created by high speed machining, carbon is
soluble in iron, leading to greatly increased wear on diamond tools as compared to other alternatives. Common
industrial adaptations of this ability include diamond-tipped drill bits and saws, or use of diamond powder
as an abrasive. Industrial-grade diamonds are either unsuitable for use as gems or synthetically produced,
which lowers their value and makes their use economically feasible.

Color

Diamonds can occur in nearly any color, though yellow and brown are by far the most common."Black" diamonds
are not truly black, but rather contain numerous dark inclusions that give the gems their dark appearance.
Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly
pure diamonds are transparent and colorless. Most diamond impurities replace a carbon atom in the crystal
lattice, known as a carbon flaw. The most common impurity, nitrogen, causes a slight to intense yellow
coloration depending upon the type and concentration of nitrogen present.The Gemological Institute of
America (GIA) classifies low saturation yellow and brown diamonds as diamonds in the normal color range,
and applies a grading scale from 'D' (colorless) to 'Z' (light yellow).

History and gemological characteristics

Diamonds are thought to have been first recognized and mined in India (Golconda being one of them), where
significant alluvial deposits of the stone could then be found along the rivers Penner, Krishna and Godavari.
Diamonds have been known in India for at least 3000 years but most likely 6000 years.The most familiar
usage of diamonds today is as gemstones used for adornment a usage which dates back into antiquity.
The dispersion of white light into spectral colors, is the primary gemological characteristic of gem diamonds.
In the twentieth century, experts in the field of gemology have developed methods of grading diamonds and
other gemstones based on the characteristics most important to their value as a gem. Four characteristics,
known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are
carat, cut, color, and clarity.