LONDON — De Beers, the world’s largest diamond producer by value, said earnings halved in the first six months of the year amid tough trading conditions, compared to a bumper start to last year, with the remainder of 2012 set to remain challenging.

De Beers, which vies with Russia’s Alrosa for the title of the world’s largest diamond producer, said profit before finance charges and taxation for the first half totalled $502 million, from $1,02 billion reaped the first six months of 2011.

Total sales dipped to $3,3 billion from $3,9 billion in the first half a year ago, while diamond production dipped to 13,4 million carats as the producer continued to focus on repairs and maintenance, while it awaits improved demand from key clients, known as sightholders.

“De Beers expects trading conditions in the mid-stream to remain challenging during the second half of 2012,” the company said in a statement. “De Beers will continue to produce in line with sightholder demand and invest in stimulating and capturing consumer demand growth.”

Anglo American, which owns a 45% stake in De Beers, agreed in November last year to take majority control of the miner by buying out the Oppenheimer family stake.