The head of De Beers Group, which controls 40 percent of the global diamond trade, said Monday that the industry must develop new markets in China and India in order to avoid being overly dependent on sales to the United States, but he did not advocate replacing the US dollar as the main currency of the international gem trade. Speaking at an international conference on rough diamonds in Tel Aviv, De Beers managing director Gareth Penny said the dollar's continued decline against the euro and other major currencies raised questions about its continued suitability. "There are people speculating that we are in a structural period of weakness for the major currency of our business," he said. "What are we going to do about that?" But in comments afterward to The Associated Press, Penny said that De Beers was not suggesting a currency switch.