(IDEX Online) - De Beers suffered a drop in revenue of almost 36 per cent in 2023, down from $6.6bn to $4.3bn.It blamed a rise in polished diamond inventories, increases in inflation and interest rates, macro-economic challenges an the rising supply of lab growns.The UK-based miner expects industry conditions to remain challenging in the short term. But the long-term outlook is favorable, it says in its preliminary financial results for 2023, published on 22 February."Over the course of 2024, assuming a measured approach from producers to the release of upstream inventory, the high midstream inventory levels seen in 2023 are expected to decline as retailers replenish their stocks," the company says."Limited consumer demand growth and ongoing retailer caution are anticipated ahead of an expected return to growth into 2025."Total production across its mines in Botswana, Namibia, South Africa and Canada fell by 8 per cent year-on-year to 31.9m carats.Total rough diamond sales fell by 19 per cent to 24.7m carats and average price per carat fell by 25 per cent from $197 to ?$147.Pic shows rough diamond sorting, courtesy De Beers.