(IDEX Online) - Alrosa's sales of rough and polished diamonds soared by a third in the last quarter of 2020, up to $1.22bn (q-on-q).The Russian state-owned miner reported average realized prices in Q4 were down by 38 per cent to $67.40 per carat q-on-q.But by the end of the year demand for for rough diamonds had become strong and stable, it said in its Q4 and 12M 2020 operating results, "driven by a balanced sales policy of major diamond producers seeking to meet real demand, along with a seasonal uptick in demand and robust performance across all segments of the diamond market."Diamond production during the period fell 23 per cent q-o-q to 7.1 m cts and for the full year it was down 22 per cent to 30m carats. The original pre-Covid forecast for the year was 34.2m carats.Alrosa shifted just over 10m carats of its 30m-carat excess inventory, which it had stockpiled during a period of weak demand because of the pandemic.