London-listed Petra Diamonds has sold its recently recovered 342.92 ct Type IIa white diamond and an 18.30 ct Type IIb blue diamond into a partnership with Stargems.

Petra will receive an upfront payment of $10-million for the 342.92 ct diamond and $3.5-million for the 18.30 ct diamond. It will also retain a 50% profit of the proceeds from the sale of the polished diamonds when sold.