A deep red gemstone, a variety
of corundum colored by a minute proportion
of chromium ions. It is found significantly
in upper Burma, Thailand, and Sri Lanka, and is far more precious than diamond.
The name has been used for other red stones, chiefly varieties of garnet and spinel. Rubies have been synthesized
by the Verneuil flame-fusion process (1902). They are used to make ruby lasers
|Ruby crystal before faceting.
Image source: Wikipedia
AND PLANETARY SCIENCE