(IDEX Online) - Petra Diamonds reported an eight per cent drop in its revenue to $178.1m in the six months to 31 December 2020, as COVID-19 depressed prices and allowed fewer tenders to take place.The British miner said a deal to restructure some of its $650m of debt should be complete by March.The move will reportedly leave current shareholders with just nine per cent of shares in the company.Meanwhile the Williamson mine, in Tanzania, which was closed in April 2020, remains on care and maintenance and unusually high rainfall and other problems have hampered operations at at Finsch and Koffiefontein, both in South Africa. Petra has previously reported a $223m loss for the year to June 2020 after facing "unprecedented challenges". It follows the $258m loss it posted last year (2019).It sold 1,712,797 carats (H1 FY 2020: $193.9m from 1,743,807 carats sold) boosted by the $40.4m proceeds from the sale of the Letlapa Tala Collection of blue diamonds (pictured) - five stones with a total weight of 85.6 carats from the iconic Cullinan mine, in South Africa.CEO Richard Duffy said the capital restructuring marked "a significant milestone in putting the Company on a sustainable footing going forward".He added: "The continued improvement in the diamond market, with prices now back at pre-COVID19 levels, is encouraging."