(IDEX Online) - The Gahcho Kue mine, in Canada, has yielded its largest diamond since operations began there more than four years ago.The 157.38 carat gem, described as being of "of exceptional quality", will be sold later this month at a tender of special-size stones in Antwerp.Canadian miner Mountain Province has named the gem Polaris after the North Star, because of its rare natural blue fluorescence.The miner said it was a major morale boost after a year in which the industry had faced immense challenges.Gahcho Kue, a joint venture between Mountain Province and De Beers Canada on the edge of the Arctic Circle, is currently not operating because of a Covid outbreak.Polaris (pictured) is being offered for sale by the Bonas Group, with viewings from February 22 and bids closing on March 5.Reid Mackie, Mountain Province's vice president diamond marketing, said: "We are thrilled to offer Polaris at our upcoming February sale. It is an extraordinary stone, recovered at the end of an extraordinary year."