Its 49%-owned Gahcho Kué mine has rebounded well from a difficult start to the year, that saw it shut down for 22 days.

The diamond is the seventh stone greater than 300 carats dug up at the Botswana operation so far this year.

Petra said the diamond, of “exceptional” quality in terms of both its colour and clarity, will likely be sold at the September tender.

MINING.COM’s ranking of the world’s 50 most valuable mining stocks marched to a new high of $1.47 trillion at the end of the second quarter.

Diamond production rose by 134% compared to last year as consumer demand recovered, while platinum output rose 59% to 1.06 million ounces.

The company called its new indicator the ‘G-Factor for Natural Resources.’

The 62-carat diamond, named "Boitumelo" is Botswana’s largest fancy pink rough yet.

Volatile gases conserved in diamonds found in ancient rocks indicate that the basic chemical composition of Earth’s atmosphere was laid down at least 2.7 billion years ago.