Africa-focused miner Gem Diamonds (LON: GEMD) has recovered a 169.15 carat Type II white diamond from its Letšeng mine in Lesotho.

This is the fourth greater than 100-carat diamond unearthed this year at the operation, the company said.

Prior recoveries include a 113 carat and a 295 carat white Type II diamonds, as well as a 139 carat boart diamond.

Type IIa diamonds are the most valued and collectable precious gemstones, as they contain either very little or no nitrogen atoms in their crystal structure. Boart diamonds are stones of low quality that are used in powder form as an abrasive.

The prolific Letšeng mine is one of the world’s ten largest diamond operations by revenue. At 3,100 metres (10,000 feet) above sea level, it is also one of the world’s most elevated diamond mines.