Optical Character

Optical Character: a term used to designate the entirety of the optical properties of a gemstone, with special reference to the number and positions of the Optical Axes: Monorefringence or Birefringence, Uniassic Birefringence, Biassic Birefringence and Optical Sign (Positive or Negative Uniaxiality, Positive or Negative Biaxiality).

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