A Rayner refractometer (yttrium aluminum garnet prism) with a near sodium–equivalent light source was used to measure refractive index and birefringence, specific gravity was determined hydrostatically, a calcite dichroscope revealed pleochroic colors, long- and short-wave UV lamps were used in a darkened room to observe fluorescence, and absorption spectra were visualized with a System Eickhorst M9 spectroscope with a builtin light source. Internal features were observed with a standard gemological microscope and a Nikon Eclipse E600 POL polarizing microscope.