(IDEX Online) - A huge 1kg platinum coin, set with 6.5-carats of Argyle pink diamonds, smashed estimates when it sold at auction for just over US$1m.The one-off creation is the highlight of the Royal Canadian Mint's Opulence Collection, featuring gems from the iconic Australian mine that closed in November 2020.The rose gold-plated, platinum coin, known as The Ultimate, was hand set with 462 fancy vivid and fancy intense Argyle pink diamonds.It was sold to an anonymous buyer for CA$1,261,250 (US$1,006,980) after heated bidding at Heffel Fine Art Auction House, setting a new record for a coin offered at auction in Canada. The high estimate was CA$900,000 (US$718,677).The Ultimate is the crowning glory of a 436-coin collection, crafted with a total of 46.7 carats of Argyle pinks.A limited edition of five Splendour 10oz platinum coins, featuring 64 pink diamonds (1.2 tcw) with a CA$253,999 price tag, has sold out, as have the 30 2oz platinum Grandeur coins, with 30 pink diamonds (0.34 tcw) which cost CA$54,999.There are also 400 gold coins for sale, weighing 1oz and each set with 0.06 tcw.