DIAMONDS are a shareholder’s best friend. Yesterday’s prelims from Petra cap a year that has been full of positives. A six per cent increase in gross production to 1.16m carats a year and a bigger stake in the Cullinan mine, from 37 per cent to 74 per cent, were the main underlying factors. But it was the sale of a 507 carat stone for $35.3m that really flattered the results, and shareholders should remember this before getting too carried away.?These numbers are good – but they’re not as good as first seems.

That shouldn’t detract from an impressive performance. Ongoing operations are doing well, allowing the firm to focus on extracting maximum value from its recent acquisitions, especially the Cullinan and Williamson mines. The latter is on track to more than double production to 2.5m carats by the end of 2014-15.

Meanwhile, the market for diamonds goes from strength to strength. Petra says it recent tenders show a “substantial improvement” in prices while the US?market is finally on the up. These shares mightn’t be forever – but they’ll certainly do for now.