Kao Diamond Mine For Sale. Diamonds - Kao Mine Large Diamond Tender Begins in . Aug 03, 2015 · Rough diamond brokers Fusion and I. Hennig began special viewings for a tender of large rough diamonds recovered from the Kao mine in Lesotho in New York on Monday.The two highlights of tender are expected to be a 153.66-carat white diamond and a 16.94 carat-fancy yellow diamond.Viewings …