The world's finest sugilite comes from the Kalahari Manganese Field, Northern Cape, South Africa.
The chemical composition of this rare mineral is mainly potassium, sodium, lithium, iron, manganese and aluminium.
Although mostly pronounced with a soft 'g' as in 'george', sugilite should be pronounced with a hard 'g'.
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. Materials from the two countries can look very different.