The world’s top diamond producer said it had registered total sales of $3.9 billion in the six months to June 30, up from $3.0 billion the year before.

“Sales during the period have been exceptional, driven mainly by continued growth in the Middle East, Indian and Asian retail markets and their impact on rough price growth,” De Beers said in a statement.

The group said that production for the period had remained essentially unchanged at 15.5 million carats, up just 0.66 percent from the first half last year.

“Despite the ongoing turmoil with the global economy, we are encouraged by the continued strong growth in price and demand during the first six months of 2011,” it said.

“De Beers is confident that the exceptional growth in retail markets in India and Asia will continue to drive demand for diamonds.”

The London-based company, which is owned 45 percent by Anglo American, 40 percent by South Africa’s Oppenheimer family and 15 percent by the government of Botswana, said it also expected strong holiday sales in the United States.

But the group is also facing a production slow-down at its South African mines caused by a strike that began July 22.