London — Petra Diamonds has sold a 20-carat blue gem for almost $15m, a major boost for the company that’s struggling with a mountain of debt and falling diamond prices.

The company found the diamond in September at its Cullinan mine in SA, famous for producing expensive gems including those in the British crown jewels. Blue gem-quality stones are among the most valuable in the world, and the diamond sold for $741,000 per carat...

BL Premium

This article is reserved for our subscribers.

A subscription helps you enjoy the best of our business content every day along with benefits such as exclusive Financial Times articles, ProfileData financial data, and digital access to the Sunday Times and Sunday Times Daily.

Already subscribed? Simply sign in below.

Questions or problems? Email or call 0860 52 52 00. Got a subscription voucher? Redeem it now