Bicolored Combination Of Purple, Yellow
Trystine, Bolivianite, Amethyst-Citrine, Citrine-Amethyst, Golden Amethyst
Ametrine's appearance is distinctive and otherwise the key quartz indicators will be present (refractive index, birefringence, optic character and optic figure). A bull's-eye optic figure is determinative for quartz. Might also show Airy's spiral.
Stones might be piezoelectric: able to generate electricity produced by mechanical pressure,Pyroelectricity: development of opposite charges at the ends of the axis due to change in temperature and triboluminescent: luminescence produced by friction.