(IDEX Online) - Gem Diamonds has recovered another large Type II white diamond at its Letseng mine, in Lesotho.News of the 223-carat stone comes just days after the London-based miner announced a 442-carat diamond, valued at $18m.Letseng is the highest dollar per carat kimberlite diamond mine in the world and has yielded 60-plus white gem quality diamonds over 100 carats since it was acquired by Gem in 2006.In 2008 the 478-carat Light of Letseng, from the same mine, was bought by Graff for $18.4m.In March 2018 an exceptional quality D color Type IIa diamond, from Letseng sold for $40m at tender in Antwerp. In 2006, the 603-carat Lesotho Promise was recovered from the same mine.