A London-listed mining company has found a 232.08-carat white diamond at its Cullinan mine in South Africa, which experts predict could fetch up to $16m (£10m).Shares in Petra Diamonds climbed 8% after the news.The South African mine is famous for being the site of the largest diamond ever recovered, the 3,106-carat Cullinan diamond found in 1905, which was cut into stones that are part of Britain’s crown jewels.The recent find is Petra’s largest white diamond since it unearthed the 507-carat Cullinan heritage in 2009 from the same mine. That rough white diamond was given a “flawless” clarity grade and fetched $35.3m, a record price for the company.“We estimate a sales price in the order of $10m to $15m, given Gem Diamonds’ recent sale of a type-II white at about $70,000 per carat and assuming some losses for cutting/polishing,” analysts at Numis Securities said in a note.“The extra revenue would go straight to the bottom line”, Numis said.Petra, which reported revenue of about $473m in the previous financial year, declined to specify how much the diamond could fetch.A company spokesman told Reuters the stone would most likely be bought by a buyer from traditional diamond hubs such as the US, Europe, Israel or China, who could cut the stone into polished gems.“It’s more a case of the clients coming to us, rather than us needing to approach clients,” he said.Petra said it expected the diamond, that has no measurable nitrogen impurities to be sold between October and December, the second quarter of its financial year.Investors are also awaiting the outcome Petra’s sale of a rare 122.52-carat blue diamond recovered from Cullinan this year. Analysts have valued the stone at more than $35m. The sale period closes on Friday.The mining company, which has five producing mines in South Africa and one in Tanzania, sold a 29.6 carat blue diamond to the US luxury jeweller Cora International in February for $25.6m.Petra has in the past year retrieved some large blue diamonds from Cullinan, which was one of the five non-core mines it bought from Anglo-American Plc’s De Beers unit – the world’s biggest diamond producer by value.