Alexandrite

Named after Russian Tsar Alexander II. A highly dichroic, rare variety of chrysoberyl. Emerald green in natural daylight, reddish in violet by artificial light, due to its unusual absorption properties. One of the hardest and most important gemstones. A fine variety is the night stone. Iron-rich varieties are yellow, green and brown in color, and are inert under UV light or X-rays. Only alexandrite exhibits a weak, red luminescence under SWUV light. Synthetic alexandrites are produced by the Czochralski, the puling method, the flux process, and the floating-zone method.