For the period January 1 to April 23, 2013, Gem Diamonds’ rough diamond sales dropped 20 percent (on y-o-y basis) to $46.7 million, reports say. Sale of rough diamonds from its Letseng diamond mine dipped 2 percent to 29,205 carats, and the average price per carat from three tenders held dropped 19 percent to $1,599. There was a 33 percent (on y-o-y basis) drop in production to 18,775 carats.