The United States remains the world’s largest diamond market, but the rapid growth of consumers with growing disposable income in China and India is helping drive a rebound from the economic downturn four years ago. Most consumers of diamonds could be in Asia by the end of the decade.

Thanks to increased demand in the top markets, rough diamond sales are expected to rise to $26.1 billion by 2020 from $15.6 billion last year, according to an annual survey released Friday by Boston-based consulting firm Bain & Co in collaboration with the Antwerp World Diamond Centre.

“The fundamental forces point to a bright outlook for the diamond market,” said Yury Spektorov, Bain & Company partner based in Moscow and co-author of the report.

Revenue generated from rough diamond sales in the top three consuming markets this year is estimated to be $44.5 billion, 61 percent of which is generated in the United States. But the rapid ascent of personal income in China’s second- and third-tier cities will cause demand for diamond jewelry and other luxuries to expand along with that growth. This means China is likely to maintain its second-place status for years to come. India’s demand is also expected to rise, but at a slower pace.

Tiffany & Co. (NYSE:TIF) of New York and Cartier SA of Paris continue to be foreign leaders in China’s high-end jewelry market. They spend at least 5 percent of their China revenue on marketing in a highly fragmented retail scene with small shops and regional local chains dominating the market.

Meanwhile, the report says demand for diamond engagement rings by younger women in the United States is “marginally slowing” as they migrate toward purchases of other pricey consumer products, especially consumer electronics. (Are iPads now an American girl’s best friend?)

A recent report by Anglo American PLC (PINK: AAUKY) – which owns an 85 percent stake in diamond giant De Beers –predicts that China and Indian consumers, who each buy about 10 percent of the world’s polished diamonds, will continue to grow demand, to 13 percent for India and 15 percent for China by 2016. It also estimates that the global trade in finished diamonds will be about $31 billion three years from now.

The annual industry report based on a global survey of 13,000 women also predicts that demand will outpace supply next year.