Anglo American boss Duncan Wanblad admitted the diamond industry underestimated the threat from lab-grown gems, which have disrupted the market for natural stones. De Beers has seen its value written down three times in three years as rough diamond prices fell 32 per cent to $105 per carat in the first half of 2026, lower than the pandemic-hit first half of 2020. De Beers posted a cash loss of $113mn, though Anglo's overall underlying earnings rose by a third to $4bn on higher copper prices.

Wanblad said about a fifth of current natural diamond supply was "on its way out over the next 12 months" and that few operations would return. The rapid growth of cheaper lab-grown stones has led to mine closures, including De Beers pausing production at its Venetia mine in South Africa. Anglo said the sale of De Beers was "advancing" but had not chosen a preferred bidder, with a consortium led by former CEO Gareth Penny tipped as the leading group discussing a deal worth about $1bn.