A 12,100-carat rough tanzanite, which could be the third largest stone in the world, was recently discovered by TanzaniteOne at its project in Tanzania. The stone is yet to be analysed after which it would be graded for colour and clarity. The mining company expects the stone to be graded under the ‘A’ grade category as per the tanzanite classification system. After grading, the company is considering cutting and polishing the one piece into smaller parts at its in-house cutting facility.