The 552-carat yellow gem quality stone, unearthed in October, measures around 3cm by 5.5cm, almost three times the size of the next largest stone ever found in Canada, Dominion – which owns 40% of the mine – said in the news release.
"A diamond of this size is completely unexpected for this part of the world and marks a true milestone for diamond mining in North America and Canadamark diamonds overall," the company said.
The previous record for a North American diamond was also found at Diavik, located in the Northwest Territories. At 187.7 carats, the so-called “Foxfire” two billion-year-old diamond was unveiled in 2015.
The stone is one of the 30 biggest diamonds ever found. The largest on record was the 3,106-carat Cullinan, found near Pretoria in South Africa in 1905. It was later cut into several stones, including the First Star of Africa and the Second Star of Africa, which are part of Britain's Crown Jewels held in the Tower of London.
"The astonishing gemstone was uncovered while passing through the initial screening process at Diavik's recovery plant," Dominion noted.
Lucara Diamond’s 1,109-carat Lesedi La Rona is the second-biggest in record, while the 995-carat “Excelsior” and 969-carat “Star of Sierra Leone” are the third- and fourth-largest.
Dominion plans to select a partner to cut and polish the stone, of which the value has not been determined yet.
Production at Diavik began in 2003 and the mine has been a fully underground operation since 2012.