Diamond prices are poised to rise for the next four years, outpacing gold as increased spending on luxury goods in China, India and the Middle East outpaces supplies of the precious stone, analysts said.

The average price of rough, or uncut, diamonds will probably rise 9 percent to $145 a carat next year, 1.4 percent in 2013 and 4.8 percent in 2014, BMO Capital Markets analyst Edward Sterck said. The gem should gain 2.6 percent in 2015 and 3.2 percent in 2016, he said.

Demand for diamonds could grow at double the pace of supply through 2020 because of an expanding middle class in China and India, Bain & Co. said this month in a report that didn’t give price forecasts.

The two nations and the Middle East will account for 40 percent of global diamond demand by 2015, compared with about 8 percent in 2005, said Anglo American Plc., which agreed to boost its stake in De Beers, the world’s largest diamond miner, to 85 percent last month.