When the mining company Rio Tinto shows its latest batch of rare naturally colored diamonds — stones with hues of pink, red and even “deep-gray violet” — executives are delighted to go on about their beauty and scarcity.
But details about pricing? That is when the lips draw shut. “It’s quite confidential,” said a laughing Arnaud Soirat, the chief executive of Rio Tinto’s copper and diamond group. Welcome to the exclusive world of the colored diamond trade, a market where the buyer pool is slim, the supply is constricted and a carat can fetch $1 million or more.
On Wednesday, Rio Tinto came to Manhattan to introduce its latest and best colored diamonds, in the start of a tour that will include a stop in Hong Kong and another one in New York. The company’s latest cache, 58 stones, sparkled in glass cases on the 21st floor of a Chelsea skyscraper. With names like the Argyle Liberte and Argyle Isla, the total weight of all the stones was 49.39 carats, suggesting a collective value in the tens of millions — even though they all could fit in a pants pocket.
The company brings such diamonds to market once a year, unearthing the stones from its Argyle mine in Western Australia, where it might sift through 100 tons of a rock called kimberlite to collect a single carat.
As it showcases its wares, Rio Tinto invites a select few collectors, wealthy people, dealers and others to submit sealed bids for the stones in the batch. It is a selling process that has few peers in opaqueness. Besides Rio Tinto, no one knows how much bidders offer for the stones, and the company does not report how much the winning bidders pay.
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