3.39cts Oval Alexandrite, The very rare and valuable alexandrite is a transparent gemstone with a remarkable color-change property: it changes from leaf green in day light to red, mauve under incandescent light. This is influenced by the different colors in light sources; daylight contains blue light while incandescent light has a red tone. The color change can be seen in thick stones, so check the cut. Alexandrite is a hard, durable stone. Alexandrite was found on the birthday of tsar Alexander II and named after him.