Total sales increased 10 percent in the first half of the year for the De Beers Group, but the diamond giant is approaching the second half of the year with caution due to weakness in the U.S. market, the company reported on Wednesday.

In what De Beers Group Chairman Nicky Oppenheimer described in a Webcast as a “very satisfactory, pleasing first half,” total sales rose to $3.74 billion, up from $3.40 billion in the first half of 2007.

This increase included a 10 percent climb in sales of rough by the Diamond Trading Co. (DTC) arm of De Beers. The DTC recorded $3.3 billion in sales. Client demand, De Beers said, has enabled the DTC to continue to steadily increase prices.