(IDEX Online) - Petra Diamonds has concluded the debt-for-equity restructuring which should secure its future.The UK-listed miner failed to attract a buyer for its three mines in South Africa as revenues plunged and it struggled to repay $650m of debts. The deal it has now struck reduces shareholders' stake in the company to just nine per cent.Its debts have been being replaced by $337m in new notes???,?"$30m from existing debtholders and the rest converted into equity.Petra's assets include the iconic Cullinan mine, source of the largest rough gem-quality diamond ever - the 3,106.75-carat Cullinan Diamond that became part of the British Crown Jewels. The company, founded by Adonis Pouroulis in 1997, also owns the Finsch and Koffiefontein mines in South Africa, and the Williamson deposit in Tanzania, which is currently mothballed.It embarked on the restructuring last October, six months after offering itself for sale.CEO Richard Duffy said: "The restructuring will provide Petra with a stable and sustainable capital structure, significantly reduced financial burdens and greater liquidity, leaving us in a stronger position to focus on optimising the value of our diversified asset base and to deliver growth for all our stakeholders."Pic shows Petra's Finsch mine