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Forms
and Properties
Diamond is pure carbon, the element that is also the
foundation of life. Carbon has interesting chemical
properties that enable it to form a truly vast number
of compounds with many other elements. Some of these
are biologically active. Another form of pure carbon
is the mineral '-- Graphite is so easily powdered that
it is used as the "lead" in mixed with clay
for this application), and so greasy that it is ed as
a lubricant. Yet diamond is the hardest known substance,
easily scratch any other material.
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Forms
and Colors Diamond crystals occur in a variety of shapes
and forms. The most common shape resembles two four-sided
pyramids arranged. base-to ¬base and is known as
an octahedron, an eight-sided form. The directions of
easy cleavage in diamond are parallel to the octahedral
faces. |
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Other
forms seen on diamond crystals include the cube and dodecahedron,
the latter an interesting 12-sided form. Some rough diamond
crystals are combinations of several of these forms. Also
frequently present on diamond crystal surfaces are triangular
pits called trigons, believed to have formed during crystal
growth.
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DIAMONDS,
GEMSTONES & CRYSTALS
FACTS & FIGURES |
| Diamonds
occur in a wide range of colors. The most familiar
are basically white or colorless, usually with
a tinge of yellow or gray. Richly colored stones,
called fancies, are rare and highly prized. Fancy
colors include golden-yellow, blue, green, pink,
and amber.
Fine yellow diamonds with so-called "canary"
color make notable gems. Two of the best-known
yellow diamonds are the Florentine (137.5 carats)
and the Tiffany (128.5 carats).Brown and coffee-colored
diamonds are not as rare, but are seldom seen
in the trade. Orange diamonds are popular in South
Africa, but few are sold in the United States.
Green diamonds are very rare, the most famous
being the Dresden green of 48.5 carats. Diamonds
are occa¬sionally found in a greenish-yellow
hue, sometimes called "champagne color."
Blue diamonds are extremely rare.
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By
far the most famous is the Hope Diamond, weighing
44.5 carats, on display at the Smithsonian Institution
in Washington, D.C. This remarkable gem has a
somewhat metallic surface luster that reflects
light and makes the gem appear darker than it
actual ly is. Pale-blue diamonds are also known,
and violet gems are occasionally found. |
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Pale-red
and pink diamonds are very rare and although red diamonds
have been reported, an intense, fine, red gem has not yet
been authenticated. Brownish-red diamonds, on the other hand,
are occasionally seen in the diamond trade.
Localities and Formation |
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