Alexandrite was discovered by the Finnish mineralogist Nils Gustaf Nordenskiöld, (1792–1866). It was named in honor of the future Czar Alexandar Nicholavich, the Alexander II of Russia
The alexandrite variety displays a unique color change habit dependent upon the nature of ambient lighting and that is because of impurities of the element chromium.
Alexandrite results from small scale replacement of aluminum by chromium ions in the crystal structure. It's a hard gemstone (8.5 on Mohs scale) that shows different color intensity when viewed at different angles and this factor must be taken into account when cutting Alexandrite to use for jewelry.
The most desired colors of Alexandrite are those that show a clearly visible pure hue color change.
