LONDON (Bloomberg) - TanzaniteOne Ltd., the world's largest tanzanite miner, posted second-quarter sales of $5.4 million, the highest quarterly revenue in two years.

The figures are 80 percent up on the previous three months and the highest quarterly revenue since the second quarter of 2008, TanzaniteOne said yesterday in an e-mailed statement.

"This extremely encouraging quarterly revenue has surpassed both our internal recovery projections as well as market expectations," chief executive director Bernard Olivier said in the statement.

The Hamilton, Bermuda-based company also said its third official sale of the year had revenue of $2.57 million, with 191,673 carats of rough tanzanite sold at an average price of $13.40 a carat.

Tanzanite, which is 1,000 times rarer than diamonds, is mined from the world's only known deposit, at the foot of Mount Kilimanjaro, Africa's tallest peak.