In ancient India, spinel was attributed to the warrior caste. Qualified as red diamond, this stone comes primarily from Sri Lanka and Myanmar.
Spinel is a family of minerals, but only alumino-magnesian spinel is of real use for jewellery. In many deposits spinel is associated with ruby, which explains its constant confusion with the latter. Some famous rubies on royal crowns are in reality spinels.
Such well-known spinels include the "Black Prince's Ruby", a 170 carat stone worn by Henry V at the battle of Agincourt in 1415, which is now among the Crown Jewels.
There is also the famous "Timur Ruby", a 361 carat cabochon cut stone, the names of whose owners are engraved on the stone.