British jeweller Graff said Tuesday it has purchased the world's largest uncut diamond -- roughly the size of a tennis ball -- for $53 million (44.5 million euros).
Canadian miner Lucara Diamond sold to Graff the 1,109-carat gem, the Lesedi La Rona, which was found in Botswana's Karowe mine in late 2015.
"We are thrilled and honoured to become the new custodians of this incredible diamond," said company chairman, Laurence Graff, in a statement.
"The stone will tell us its story, it will dictate how it wants to be cut, and we will take the utmost care to respect its exceptional properties."
Lucara confirmed the hefty price tag in a statement issued in Vancouver.
"The discovery of the Lesedi La Rona was a company defining event for Lucara," said William Lamb, president and chief executive of Lucara.
"It solidified the amazing potential and rareness of the diamonds recovered at the Karowe mine."
The rough diamond had previously failed to meet its reserve price of more than $70 million at a Sotheby's auction in 2016.
Graff is already the owner of a 373-carat diamond, which was bought earlier this year and formed part of the original stone.
Lesedi La Rona means "our light" in Botswana's Tswana language. It could be cut into smaller gems for jewellery or left whole in a private collection.