Petra Diamonds (PDL.L) said its revenue jumped 88 percent in the year to end June, boosted by the sale of the 507-carat Cullinan Heritage diamond and the recovery in gem prices.

www.petradiamonds.com

Petra sold the Cullinan Heritage for $35.3 million in February to leading Chinese jeweller Chow Tai Fook, setting a record price for a rough diamond.

"We have only seen the stronger market in the last four to five months," Chief Executive Johan Dippenaar told Reuters.

"Last July to December was fairly subdued so even just at these levels a whole year of trading at these prices would be great."

Sales for the largest diamond producer on AIM rose to $177.7 million as output climbed 6 percent to 1.16 million carats. Petra aims to increase annual production to over 3 million carats by 2019.

"The diamond market has recovered strongly from the downturn, driven by the global economic revival and a slow but steady improvement in the important U.S. market," the company said on Tuesday.

The United States makes up about half of the global diamond jewellery market.

"Exciting demand growth continues at double digit pace from China and India, with market commentators predicting that China could grow to equal the U.S. diamond market within the next decade."

Petra said that by the end of June, rough diamond prices had returned to the levels of June/July 2008.

"Whilst we are now anticipating some consolidation in the market, there are expectations of a significantly improved year end, driven by the traditionally strong festive buying season (Thanksgiving and Christmas)."

On Monday, larger rival Gem Diamonds Ltd (GEMD.L) said both rough and polished diamond prices have strengthened over the last six months, driven by demand from China and India and improving U.S. consumption.

(Reporting by Julie Crust; editing by James Davey)