Global output of diamonds declined in 2011 on aging mines and struggling demand brought by the continuing debilitating fiscal crisis in the eurozone.

Last year, the world's diamond miners produced only 123.9 million carats of diamonds, down by 3.4 per cent from 128.3 million carats a year ago, according to latest data from Kimberly Process (KP).

"It should be said that the downward trend in global diamond production will continue to develop mainly due to the exhaustion of mine fields," KP said in its report.

"A diamond mine takes between seven to 15 years to turn it into something that produces, and no world-class mine is known at this moment to us," Shlomo Tidhar, acting Chief Executive Officer of Singapore Diamond Exchange Pte Ltd., told Bloomberg. A world-class mine can churn $700 million to $800 million or more worth of diamonds a year, he said.

"Also given the difficult market conditions, we can expect that diamond miners will cut production in line with falling demand for rough gems," KP said.

Based from KP's tally, Russia was 2011's top diamond producer at 35.1 million carats, seconded by Botswana at 22.9 million carats. The yield represented an increase of 0.8 per cent and 4 per cent, respectively, from previous records of the two countries.

Democratic Republic of the Congo and Canada came in third and fourth. However, both registered a decline in production of 13 per cent and 8.8 per cent, respectively, from a year ago.

Fifth was Zimbabwe, with a 0.7 per cent increase in production to 8.5 million carats from 8.4 million carats in 2010.

South Africa, Angola, Australia and Namibia complete the top nine diamond producing nations for 2011. However, all four countries recorded sharp falls in their output levels.

The total value of rough diamonds mined in 2011 grew to US$14.4 billion from US$11.39 million in 2010 and US$8.26 billion in 2009, KP said.

Global demand for diamonds will continue to be motivated by India and China.

"India is still the largest final consumer of rough diamonds. The country imported 132.095 million carats. The second largest diamond cutting centre is China, where net imports of rough diamonds in 2011 totalled 6.095 million carats," KP said.

The KP, according to its web site, is an international certification scheme that regulates trade in rough diamonds. It aims to prevent the flow of conflict diamonds, while helping to protect legitimate trade in rough diamonds.