South African diamond giant De Beers has recorded a 15% rise in sales for 2005, but its production has fallen short of expectations.
De Beers produces 60% of the world's diamonds
The firm sold $6.5bn worth of rough diamonds in 2005, and estimated that diamond jewellery sales rose by 6-7%.
Its output of rough diamonds reached a record 49 million carats - but the growth of 4% fell short of its 7-8% target.
The firm will spend $100m this year searching for new diamond deposits.
De Beers said that sales around the world grew in every region except Europe during 2005.
Its outlook for 2006 was "positive", it said, with growth seen similar to 2005 "in line with expectations for global economic growth".
The company controls about half of the world's diamond supply and is 45% owned by mining giant Anglo American.
The firm's marketing arm, the Diamond Trading Corporation (DTC), ships gems to London to be mixed with stones from elsewhere for onward sale.
De Beers is in the process of selling 26% of its mining operations to a black empowerment firm, Ponahalo, which is 50% owned by De Beers employees and pensioners.
The deal is part of the South African government's strategy of giving greater economic power to the country's black majority.