De Beers, the diamond mining subsidiary of mining giant Anglo American, saw a sharp rise in earnings last year.De Beers's achieved underlying earnings of $968m in 2011, against a 2010 figure of $598m.The 62% rise in earnings was revealed by Anglo American, the long time major stakeholder in the firm which took a controlling interest in November of last year.For full year 2011 however, Anglo will only receive 45% of the earnings - the level of its stake before the takeover. This amounts to $443m, versus $302m last year.The significant increase in earnings over 2011 emphasises the case for the $5.1bn transaction, which ended the Oppenheimer family's 80-year involvement in De Beers.What seems to have rankled some observers however, and may be contributing to a fall today in shares of Anglo American, is that De Beers has announced a small fall in its annual production, adding that it expects to continue to rein in output growth in 2012.BS