Petra Diamonds has sold the 232.08 carat white diamond discovered at its Cullinan mine in South Africa in September for $15.22m.It was bought by Diacore, a multinational diamond company.Chief executive of the FTSE 250 group, Johan Dippenaar, said: "We are delighted to have achieved the sales result for this exceptional white stone, which is an outstanding example of the very high quality, large diamonds produced at Cullinan."Shares climbed 1.41% to 180.30p by 12:28.