Vancouver-based Lucara Diamond Corp. has failed to sell the tennis-ball sized diamond it discovered at its Botswana mine last November.
The 1,109-carat Lesedi La Rona diamond drew a high bid of US$61 million at the Sotheby's auction in London, falling short of the reserve price.
Sotheby's touted the diamond as the largest gem quality rough diamond to be discovered in over a century, and the largest known to exist today.
The auction house said the Lesedi La Rona diamond is second in gem-quality size only to the Cullinan Diamond, which was discovered in 1905 and later cut into nine smaller diamonds.
Still, the stone was unable to draw bids to match the reserve price, which was not disclosed, and even fell short of the US$63.1 million that Lucara got for an 813-carat rough diamond its sold privately in May.
The name Lesedi La Rona means "our light" in the Tswana language spoken in the area where the diamond was found.
Stock in Lucara was down 49 cents or 12.5 per cent at $3.43 in afternoon trading on the Toronto Stock Exchange.