The annual sale of Rio Tinto\'s rare pink-hued diamonds attracted unprecedented interest with at least two of the stones fetching record prices of over $2 million, the mining giant said Monday. The 2013 Argyle Pink Diamonds Tender of 64 red, pink and blue stones drew a record number of bids over $1 million from established markets such as Japan and Australia as well as emerging markets China and India. The highlight was the Argyle Phoenix, a 1.56 carat gem and one of three Fancy Red diamonds on offer, which sold for more than $2 million to a Singapore-based jeweller, the highest per-carat price paid for any diamond ever produced from Rio\'s Argyle mine in Western Australia. The exact price was not disclosed due to client confidentiality. Another record was set for the Argyle Dauphine, a 2.51 carat Fancy Deep Pink diamond, which also sold for more than $2 million, to a US-based dealer. Rio\'s Pink Diamonds manager Josephine Johnson said the prices reflected \"increasing demand from the world’s top jewellers, designers, collectors and connoisseurs\". \"These fabulous flukes of nature are a good news story in the mining industry at the moment,\" she told AFP. There was a lot of interest from our established markets such as Australia, the United States, Japan and Europe but also China and India, where there is now very strong demand.\" A pink diamond is usually worth about 50 times more than a white diamond, although a 118.28-carat white diamond broke a world record earlier this month when it fetched more than $30 million at a Hong Kong auction. Given the rare pink stones are only offered once a year and demand is high, previews were held in Sydney, New York, Tokyo, Hong Kong and Perth earlier this year to allow clients and experts to see the gems and make offers for individual diamonds. The Argyle mine produces virtually the entire world\'s supply of pink diamonds, with the red seen as the pinnacle of the colour scale. It is not known how the diamonds acquire their rose tinge but it is thought to come from a molecular structure distortion as the jewel forms in the earth\'s crust or makes its way to the surface. \"We are delighted with the results for the 2013 Tender collection which are a reflection of their rarity, provenance, and global reach,\" said Rio Diamonds managing director Jean-Marc Lieberherr. \"The Argyle ore body is extraordinary and after 30 years of production it continues to produce the world’s most coveted diamonds.\"