Red coloured natural corundum.
Derived from the Latin ruber, red, the name ruby dates from the 13th Century. The ruby has always been held in high esteem; it was known in India by the sanskrit term ratnaraj, queen of precious stones.
With its evocation of blood and fire, the ruby is naturally associated with courage, and is a royal insignia borne by kings on their crowns or their helmet.
The substitution of some aluminium by chromium causes the red colour of ruby, as well as its vivid red luminescence under black light. It is preferably cut with the table perpendicular to the line of sight in order to bring out its best colour.
The various deposits are found in Myanmar, Vietnam, Thailand & Cambodia, Sri Lanka, India, Kenya and Tadjikistan.