RAPAPORT... Rio Tinto achieved record value at its 2020 Argyle Pink Diamonds Tender, after bidders raised prices for the rare stones as supply has come to an end.The company offered 62 pink, red, blue and violet stones, weighing a total 57.23 carats. It allowed participants to view the goods using livestreaming and a virtual portal at locations in Antwerp, Singapore and Perth, Australia, due to travel restrictions associated with the coronavirus pandemic.Hong Kong-based Kunming Diamonds won 30 of the lots on offer, including the coveted Argyle Eternity. The 2.24-carat fancy-vivid-purplish-pink now ranks as the most valuable fancy-vivid diamond in the event's 37-year history, Rio Tinto said last week. Another record fell as an oval-cut, 0.70-carat, fancy-dark-violet-grey diamond set a new bar for the most valuable stone of its color produced at the mine. Rio Tinto did not disclose pricing information from the tender. The Argyle mine ceased operations on November 3 after nearly four decades of activity, thus cutting off the primary source of rare pink, red and violet diamonds to the market. The value of Argyle pink diamonds sold at tender has appreciated by more than 500% over the past two decades, outperforming all major equity markets, the company noted.The stones continued to appreciate this year, since supply is being diminished, participants observed. "As next year will be the last Argyle tender, we bid on all stones, [since] the goods [will] become super rare, in [high] demand, and expensive," said Shmulik Polnauer, an executive at Leibish & Co., an Israel-based colored-diamond trader, which won 16 stones. Polnauer estimated that asking prices at the tender were 15% higher than at the 2019 tender. Leibish added "20% and more" to its bids to make sure the company secured lots, he revealed.Rio Tinto also sold 12 sets of miniature rare Argyle colored diamonds weighing a total of 13.90 carats, called the Petite Suites, which saw strong competition, it noted. The stones in each set - which the miner curated over a five-year period - were matched to include a balance of size, shape, color and clarity. Australian jeweler John Calleija, who successfully bid on a number of those sets, was already exploring design possibilities with the new stones, he said."We are delighted with the results of the 2020 Argyle Pink Diamonds Tender, a testament to the unique Argyle ore body and its place in the history of the world's most famous diamonds," said Patrick Coppens, general manager of sales and marketing for Rio Tinto's diamonds business.The miner will hold its final Argyle Pink Diamonds Tender from the last remaining ore production next year.Image: The Argyle Eternity diamond. (Rio Tinto)