Chrysoberyl / Alexanderite

Color: Chrysoberyl - Golden-yellow, greenish to brownish.

Alexandrite - Color change from green to purple or red. Moh’s hardness: 8.5

Refractive Index: 1.744-1.755

Critical Angle: 35°

Specific Gravity: 3.70-3.72

Cleavage: Imperfect

Fracture: Weak, conchoidal

Dispersion: Medium (.015)

Heat Sensitivity: Can be, cracks and cleavages may open up and travel with heat.

Dichroic: very weak (reddish to yellowish or yellow to pale-green)

Birefringence (double refraction): Medium (.011)

Crystal Structure: Orthorhombic

Treatments: Generally none, sometimes can be irradiated.