This is the polished blue violane sphere. Diameter 2″ (51mm). Weight — 7.2oz (205 grams). Origin: Russia, Transbaikalia.
Some information about violane:
Violane is a variety of the diopside mineral bluish tones. Violane color is due to admixture of manganese and iron. Contains 10% jadeite and aegirine components.
Known deposits from Italy (Saint-Marcel, Piedmont) and Russia. In Russia deposits are located in the Transbaikalia, Altai and Sayan.