Natural Alexandrite 3.5cts 9x7mmGIA Certified Natural Alexandrite 3. 5cts 9x7mm Descriptions Alexandrite, with its chameleon like qualities, is a rare variety of the mineral chrysoberyl. Its color can be a lovely green in daylight or fluorescent light, changing to brownish or purplish red in the incandescent light from a lamp or candle flame. This is a result of the complex way the mineral absorbs light. Please refer to the features below for more information about this stone.