Crystalline:
- Possessing a definite and regular internal atomic structure.
- Characteristic geometrical external forms.
- Directional properties that vary with the orientation of the crystal (except those forming in the cubic crystal system)
- Products often formed through slower cooling.
- Physical and optical properties identical in all crystalline substances belonging to the same species and/or variety.
Non-Crystalline:
- Possessing no-orderly internal atomic structure.
- No naturally-occurring characteristic external shape.
- Properties that are the same in all directions (non-directional).
- Products often formed through rapid cooling.
- Physical and optical properties identical in all non-crystalline substances belonging to the same species and/or variety.
Gemstones can also be classified as either:
Massive: a term used to describe a crystalline substance that does not have a naturally occurring external characteristic shape (i.e. rose quartz) or is composed of masses of small crystals.
Cryptocrystalline or Microcrystalline: a term used to describe material that has grown, not as a single crystal, but as an aggregate of small or microscopic crystals unrecognizable to the naked eye. The tiny component crystals are in a scattered orientation within the body of the gem. These gemstones are usually semi-translucent to opaque and are slightly porous. Although all cryptocrystalline gems are massive, it should be noted that not all massive gem materials are cryptocrystalline (i.e. chalcedony quartz)
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Sincerely,
Jack Ghazalian
Director of Corporate & Career Development USA
