Petra puts “exceptional” 39-carat blue diamond up for sale

The Madrid-based firm signed a $20-million-dollar contract.

The colour properties of prehistoric copper alloys have largely been understudied. Until now.

The two have committed to holding equal stakes for the first six years of the company's existence, said Thyssenkrupp personnel chief Oliver Burkhard.

With this purchase, Graff Diamonds says it has acquired, cut and polished the majority of the top 21 largest stones of the 21st century.

The state-run company said it wants to increase its total coking and thermal coal output to 18.2 million tonnes in 2030 from 15.6 million expected in 2018.

Launching deliverable futures for gold in 2018 is a move to further prop up bullion market liquidity, said bourse chief exec Alexander Afanasiev.

More than half the 2017 combined market cap gains for the world's largest listed miners accrued to just five firms as gold producers drop out of top 10.

Investors becoming impatient with pace of its restructuring, putting pressure on CEO Hiesinger to fix underperforming units and revive flagging share price.

The government says the cleric violated the Mines and Minerals Act.