Workers at Lesotho’s Letšeng mine have discovered an absolute whopper of a diamond, rated at 910-carats. Roughly the size of two golf balls, the precious gem has an estimated value of $40 million. The rock, uncovered in the landlocked southern African country of Lesotho, is a 910-carat, D-color Type IIa diamond. This type of diamond makes up about 1 to 2 percent of all natural diamonds, containing no measurable impurities such as nitrogen atoms.