Petra Diamonds’ rough prices have started to rebound, initial results from its latest tender indicated. The first part of the trading session brought in $58.7 million from the sale of 462,794 carats, at an average price of $127 per carat, Petra said last week. Prices were 20% higher on a like-for-like basis — comparing similar categories of diamonds — than at the fiscal year’s second tender, which ended in October. Prices of rough under 2