Sugilite is a relatively rare mineral made up primarily of potassium, sodium, lithium, iron, manganese and aluminium.
The world's finest material comes from the Kalahari Manganese Field, Northern Cape, South Africa.
Geologists believe this area is between two and three billion years sold.
Although usually pronounced with a soft 'g' as in the name 'George', sugilite should be pronounced with a hard 'g' as in 'goat'.
Sugilite was initially discovered in Japan in 1944. It was incorrectly believed to be a type of Eudialyte.
The deposit in South Africa was discovered in 1973. Material from the two countries can look very different.
SODALITE
