The coloured gemstones specialist, which recently completed the acquisition of the iconic Fabergé brand, said the 75% owned Kagem mine produced 6.6mln carats in the fourth quarter of 2012, a sharp increase on the 3.9mln carats produced in the corresponding period of 2011.

The grade for the quarter improved to 288 carats per tonne from 222 carats the year before, while the unit production costs came down to US$0.66 per carat from US$0.87 per carat a year earlier.

Cash rock handling costs were US$3.43 per tonne in the fourth quarter, as against US$3.21 per tonne the year before.

Unit ore production costs declined to US$189 per tonne from US$193 per tonne.