A Tanzanian small-scale miner, who became an overnight millionaire in June for selling two rough Tanzanite stones valued at $3.4m, has sold another gem for $2m. The third discovery by Saniniu Laizer weighed 6.3kg. Tanzanite is only found in northern Tanzania and is used to make ornaments. It is one of the rarest gemstones on Earth, and one local geologist estimates its supply may be entirely depleted within the next 20 years. The precious stone’s appeal lies in its variety of hues, including green, red, purple and blue. Its value is determined by rarity – the finer the colour or clarity, the higher the price. Mr Lazier urged his fellow small-scale miners to work with the government, saying that his experience was a good example. “Selling to the government means there are no shortcuts… they are transparent,” he said in his remarks at a ceremony in the northern Mirerani mine. Artisanal miners often complain about late payments of their royalties by mine owners.