The price hike by the group's marketing arm, the Diamond Trading Company (DTC), came amid strong demand for diamonds in Asian emerging markets and tight supply, which led to price increases of 8.5 percent earlier this year.
A De Beers official said last month that buoyant diamond demand from
De Beers, 45 percent owned by mining group Anglo American (AAL.L: Quote, Profile, Research ), made the price increase during the firm's July "sight" this week, one of 10 week-long events during the year at which the DTC markets rough diamonds to tightly-screened clients.
"Some increases have been made at the July Sight, the overall effect of which is plus 5 percent," De Beers said in an email in response to a query.
De Beers said in February that it expected a rebound in its rough diamond sales this year after a dip in 2007.
Sales fell 3.7 percent to $5.9 billion (2.97 billion pounds) last year, but supply shortages were expected to keep prices strong and help to lift the 2008 sales figures, De Beers had said.
De Beers, which controls around 40 percent of the diamond market, posted flat output of diamonds last year at 51 million carats and a steady result is expected in 2008.