An understanding of basic crystallography not only allows us to appreciate the beauty of gemstones in their uncut, natural state but can also aid in their identification.
Crystalline & Non-crystalline
Crystalline:
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Possessing a definite and regular internal atomic structure.
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Characteristic geometrical external forms.
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Directional properties that vary with the orientation of the crystal (except those forming in the cubic crystal system)
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Products often formed through slower cooling.
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Physical and optical properties identical in all crystalline substances belonging to the same species and/or variety.
Non-Crystalline:
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Possessing no orderly internal atomic structure.
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No naturally-occurring characteristic external shape.
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Properties that are the same in all directions (non-directional).
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Products often formed through rapid cooling.
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Physical and optical properties identical in all non-crystalline substances belonging to the same species and/or variety.
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