RAPAPORT... Mountain Province saw rough prices rise 8% on a like-for-like basis at its first sale of the year, as demand strengthened.The miner sold 241,827 carats from its Gahcho Ku?(C) mine in Canada - jointly owned with De Beers - for $21.8 million at this month's tender in Antwerp, averaging $90 per carat, the company reported Monday. Average prices at that event, which closed January 22, surpassed the $61 per carat achieved at last month's sale."The first sale of the year was excellent - the growing confidence amongst rough-diamond buyers translated into a healthy price improvement...when compared to our record high-volume December sale," said Mountain Province CEO Stuart Brown. "We expect to see a continuation of the positive trend as rough and polished markets continue to strengthen post a successful retail season."At the February tender, Mountain Province will sell a 157-carat diamond that it recovered recently. The stone, named Polaris after the North Star, exhibits a natural blue fluorescence, and is one of several high-value stones the miner will offer at the sale.Image: The 157-carat rough diamond. (Mountain Province)