According to reports, De Beers has prepared a list of companies interested in bidding for the unprofitable Cullinan diamond mine in South Africa.%%Upon the conclusion of a due diligence process, which involves mine inspections and information gathering, the bidders would be asked to submit binding offers for the Cullinan mine.%%De Beers would then enter into negotiations with one of more of the invited bidders, the company said in a statement.%%While De Beers spokesperson, Nicola Wilson, refused to divulge any details about the bidders, Miningmx.com said that Rio Tinto and Petra Diamonds may be in the running, according to its own market sources.%%Wilson indicated that the sale is likely to be completed by the year-end or in early 2008.