Purple to Reddish Purple Chrysoberyl from Brazil.

Mineralogical and gemmological data of two intensely coloured chrysoberyls from Brazil are presented. Both samples are twinned, and they appear violet-purple or purple in daylight, and reddish purple or red-purple in incandescent light. They have good transparency, but appear very dark in reflected light due to their enriched chromium contents. In one sample, an average of 1.54 wt.% Cr₂O₃ was measured, together with 0.60 wt.% Fe₂O₃. The high Cr content is responsible for a reduced transmission in the blue-green range of the visible spectrum, which causes a shift in the daylight coloration from blue-green for typical Cr-bearing chrysoberyl (alexandrite) to violet-purple or purple for such samples with distinctly higher Cr values. [ABSTRACT FROM AUTHOR]