Diamonds may be forever but they are also seriously on sale. Natural rough diamond prices have collapsed 26 per cent in the past couple of years. Tepid US and Chinese demand for diamond jewellery hasn’t helped. But most ring fingers point at the increasing popularity of cheaper laboratory grown diamonds (LGD). This fracturing of the diamond market is set to last.

After a brief pandemic-era boom in diamond jewellery, miners are battling to whittle down oversupply of gems. Anglo-American’s De Beers, along with Russia’s Alrosa, control two-thirds of the rough diamond supply. DeBeers this week said its rough sales dropped 23 per cent in the first quarter.

It is not enough. While rough stone inventory has stabilised of late, polished diamond stocks remain high. At more than $20bn at the end of 2023, these were near five-year highs, up a third since the end of 2022, according to Bank of America. Worse, as LGDs have taken market share, their prices have declined too, to about 15 per cent or less of their natural counterparts.