RAPAPORT... Gem Diamonds has unearthed a 254-carat rough stone in Lesotho, marking a return to high-value discoveries following a lull.The "high-quality," type II, white diamond came from the company's lucrative Let??eng mine, it said in a statement Tuesday.The miner had not publicized any noteworthy finds since January, when the deposit produced a 146.9-carat rough. Output of large diamonds was sluggish in the first quarter because of the nature of the areas of Let??eng the company accessed during the quarter, CEO Clifford Elphick said last month.Image: The 254-carat diamond. (Gem Diamonds)