Rio Tinto is launching one of its last ever pink diamond tenders as it prepares to shut the only pink diamond mine in the world.
The miner has put 63 of its rare pink diamonds from its West Australian-based Argyle mine up for tender, with prices expected to run to nearly $100 million for the entire lot.
Every year, Rio Tinto selects its best pink diamonds to sell to the world’s wealthiest people, and this year’s auction features the largest ever vivid pink diamond since its sales began in 1984, Rio Tinto’s chief executive Jean-Sébastien Jacques told Fairfax Media.
The largest diamond in the 2018 tender is the Argyle Alpha diamond, weighing 3.14 carats, which was actually uncovered in 2015.
Before it was cut, the Alpha pink diamond weighed 5.88 carats.
While the process of creating regular diamonds is well understood – with diamonds able to be synthetically created – it is not yet known why pink diamonds are pink.
The largest ever pink diamond recovered from the Argyle mine, the Pink Jubilee, weighed 12.76 carats.
Although Rio Tinto has not set a price on Alpha, the record price achieved for a pink diamond was $US2.2 million per carat, potentially valuing Alpha at around $US7.9 million ($10.7 million).
The most expensive gem ever sold at auction was the 59.6 carat Pink Star diamond, sold for $US71.2 million last year.
The buyers are typically the super-wealthy, or luxury jewellery businesses from around the world. They are allowed to bid by invite only.
“It’s a niche market, there are very few people who are invited to bid. All the bids will be received before the 10th of October, and at that point, we will disclose who are the winners,” Mr Jacques said.
“Last year’s auction was very good and we expect 2018 to be even better.”
The tender starts in Sydney before moving to Hong Kong and finishing up in New York.
However, this could be one of the last auctions with pink diamonds.
Mr Jacques said the world is about to lose its main supply of pink diamonds as its Argyle mine is approaching the end of its supply. Argyle accounts for about 90 per cent of the world’s pink diamonds, with the remaining 10 per cent being random finds in other diamond mines.
“This is the only mine which has consistently produced these types of diamond,” Mr Jacques said.
“It took only a few billion years to produce them all. The mine has only a few years left, about three years.”
While Rio Tinto is shutting down the Argyle mine, it still operates the Diavik diamond mine in Canada’s frozen far north.
“We like diamonds, which is why we have comprehensive exploration for diamonds. It takes a lot of time and a lot of dedication, and we hope to find a new mine like Argyle, but we have to be patient,” Mr Jacques said.