(IDEX Online) - Alrosa reports a drop of 20 per cent in rough diamond sales (quarter-on-quarter) - and a rise of 22 per cent in its gem quality price index (year-on-year).The Russian state-owned miner says global stocks are at their lowest levels for years, pushing prices up as supply struggles to match the bounce-back in consumer demand."Jewelry demand is strong in all the key markets," it says in its Q3 production report. "At the same time, rough diamonds stocks at miners are at minimal levels as supply structurally dropped. The company sees a limited risk of any meaningful supply response globally."Alrosa has been topping up its dwindling inventory with rough from the Gokhran mineral repository. It says its own stocks have increased marginally to 8.6m carats, from 8.4 carats in Q2.It concludes that end demand is stable, buoyed by Christmas demand, midstream has been gradually ramping up its cutting capacity, and supply shortages will continue to be offset by a recovery in rough diamond prices.Alrosa's diamond production during the quarter was 8.8 m carats. Proceeds from rough and polished diamond sales totaled $938m.Pic courtesy Alrosa