The changes in the American diamond trade for the month of May fell along the axis of rough and polished: both imports and exports of rough diamonds fell, while both imports and exports of polished diamonds rose, Diamond World reports.

America's imports of rough diamonds in May fell by a modest 4% to reach $53 million, but the country's exports of rough diamonds dropped by a staggering 44% to hit just $15 million. As a result, the U.S. net rough imports for May rose by 34%, totaling $38 million.

The U.S. imported 1.5 million carats of polished diamonds in May, which was only negligibly different from the number recorded in May 2012. But since the average price of the polished diamonds it imported rose by 23%, the total value of the diamonds also rose by a commensurate 22%, to reach $3.192 billion. Likewise, America's exports of polished diamonds rose by 13% to reach $1.485 billion worth, according to Diamond World.