(IDEX Online) - Mountain Province has recovered the biggest ever diamond from its Gahcho Kue mine in Canada - a 157.4-carat gem of "exceptional quality".The miner said it was a major morale boost after a year in which the industry had faced immense challenges.Gahcho Kue, an open pit operation approximately 280 km northeast of Yellowknife, Northwest Territories, began commercial production in March 2017.Mountain Province Diamonds, which jointly operates the mine with De Beers, said it sold 956,348 carats during Q4 for $61.7m - an average value of $64.53 per carat.That's up slightly on a tender in Antwerp in October, in which it sold $34.3m of rough for an average of $61 per carat.It said it was very encouraged by the continued price recovery in Q4, with most sales categories finishing above pre-COVID-19 values. Stuart Brown, the company's president and CEO, said: "Rough diamond prices, in the larger and better-qualities have been exceptional and pleasingly we saw further improvement in the smaller and lower quality diamonds which we believe will continue to strengthen in 2021.Pic shows the newly-recovered 157.40-carat diamond