The world's second-largest diamond has been sold for just over $50m, just over a year after going unsold at an auction in London.

Vancouver-based Lucara Diamond said on Monday (25 September), the 1,109-carat Lesedi La Rona tennis-ball-sized diamond was sold for $53m (£39m), or $47,777 a carat to Graff Diamonds. A year ago, the stone, the biggest diamond uncovered in over a century, failed to find a buyer at a Sotheby's auction in London, where it had been expected to fetch around $86m.

The Canadian company, which is famous for producing some of the world's best and biggest stones, recovered the diamond in its Karowe mine in Botswana nearly two years ago.

The Lesedi La Rona - "Our light" in the Tswana language spoked in Botswana - is the second-biggest diamond ever recovered since the Cullinan Diamond, a 3,106-carat gem was discovered in South Africa in 1905.

The latter was subsequently cut to form the Great Star of Africa and the Lesser Star of Africa, which are set in the British Crown Jewels.

Lucara revealed it had originally hoped to sell the Lesedi La Rona for around $70m, but accepted Graff's bid as it topped any of the offers it received at the Sotheby's auction last year. However, the price falls short of the $63m the company received last year when it sold the 813-carat The Constellation diamond to Dubai-based Nemesis International.

Graff Diamonds founder Laurence Graff said: "The stone will tell us its story, it will dictate how it wants to be cut."

The London-based firm has a history of buying precious stones in landmark deals and acquired the 603-carat uncut Lesotho Promise at an auction in Belgium for $12.4m in 2006.