RAPAPORT... Rough diamond trading was robust in February, with De Beers notching $555 million in sales during the month. Prices remained strong, fueling concern among sightholders that their profit margins were tightening."We had a good few months, and polished prices have increased. That has encouraged the mining companies to raise their rough prices," a Mumbai-based supplier said at last week's Hong Kong International Diamond, Gem & Pearl Show. Manufacturers are making money from old polished, but new supply is less profitable due to higher rough prices, he added.De Beers increased prices slightly, but also changed the assortments in boxes to include more high-value goods, resulting in a more expensive sale for sightholders, dealers explained. There was good demand for 1- to 2-carat rough, that yields 0.30- to 1-carat polished diamonds, for which there is steady interest from buyers, dealers noted in Hong Kong.De Beers boxes were selling at around 5% premiums on the secondary market during last week's sight, slightly down from January, according to Bluedax, an online rough brokerage.The current level of demand is in line with expectations, following strong diamond-jewelry sales during the US holiday season, said De Beers CEO Bruce Cleaver. He also noted positive signs for consumer spending over the Chinese New Year.The company recorded sales of $1.23 billion in the first two months of the year, which is 4% below the same period last year. Still, De Beers is expecting stronger sales this year, after raising its production outlook to between 34 million and 36 million carats, versus 33.5 million carats recovered last year.