RAPAPORT... Gem Diamonds has unearthed its fourth 100-carat-plus diamond this year from its Let??eng mine in Lesotho, the company reported Monday. The discovery of the D-color, type IIa stone followsthe recovery of a 910-carat, D-color diamond from Let??eng last week, believed tobe the fifth-largest rough in history. The miner also uncovered two D-colorstones weighing 117 carats and 110 carats earlier this month. Last year, Gem Diamonds began extracting ore from ahigher-grade part of Let??eng, resulting in an increase in its recovery of large stones.