The reality star's rock has gone under the hammer

The engagement ring that Kim Kardashian received from ex-husband Kris Humphries has sold at auction for an impressive $620,000.

An unidentified buyer won the 16.21 carat Lorraine Schwartz diamond at Christie’s in New York yesterday, paying a huge $749,00 (£470,000) including the house’s mark-up.

Some of the proceeds will go to an unnamed charity.

Kris, 28, proposed with the sparkler – first reported to be worth $2 million – in May 2011 but Kim, 32, gave it back after their 72-day marriage ended five months later.

The NBA player chose to auction it off when their divorce was finalised in June.

It hasn’t been confirmed that the rock at Christie‘s was Kim‘s but a representative says it has the same dimensions and that a ‘gentleman’ brought it in.

Kim has been waiting for the day he would auction it,’ a source tells Us Weekly.

‘Everyone always asked what Kim did with the ring – she silently gave it back over a year ago. And Kris waited until the divorce was final to sell it.’

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Anna Duff