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Gemstone
Properties
We know the world around us by means of our senses.
Every object has certain physical and chemical properties
by which it can be identified are measurable by various
techniques. Modern chemistry is Sophisticated and precise,
but usually beyond the capabilities of the jeweler.
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The
practical retailer, who may not have a chemical laboratory
x his disposal, must therefore rely on various optical
and physical properties for identification and evaluation. |
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Most
gems are minerals, which are crystalline substances. In all
solids the constituent atoms are arranged in geometric arrays,
like a kind of three-dimensional wallpaper pattern.
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Gemstone Properties |
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atoms have fixed positions relative to one another,
resulting in an internal regularity that affects
the external shape of crystals, as well as their
properties.The atoms in crystals are held together
by strong electrical forces called bonds.
The bond strength within a solid varies with direction,
somewhat like the grain of a plank of wood. A
pine board may split easily along the grain, but
will break irregularly, if at all, across the
grain.
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In
crystals, planes of weak bonds are directions
of cleavage, or easy splitting. The way a crystal
breaks is thus diagnostic of its internal atomic
arrangement and is useful in identification. |
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Inclusions
in gemstones are also sometimes diagnostic, not only of identity,
but also of country of origin. Inclusions are foreign materials
incorporated in a crystal at the time of growth. In the case
of emeralds they can actually indicate the specific mine from
which a crystal came. many of the properties used in identification
by the gemologist also affect the value of cut gems. |
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