Blue Moon diamond sold for $48 million 'bought for billionaire's seven-year-old daughter'

The 'Blue Moon' is 'the most expensive jewel ever sold at auction'

The 12.03-carat blue diamond auctioned by Sotheby's in Geneva (AFP/Getty Images)

A Hong Kong billionaire is believed to have bought one of the largest known blue diamonds worth $48.4 million - for his seven-year-old daughter.

The rare 12.03-carat jewel formally named “Blue Moon” was the main showpiece of Sotheby's 'Magnificent Jewels and Noble Jewels' sale in Geneva on Wednesday.

The buyer is said to have immediately renamed the gem “The Blue Moon of Josephine” after his daughter, according to the South China Morning Post.

The sale comes after the same man supposedly spent $28.5 million buying a rare 16.08-carat pink diamond – the largest of its kind ever to be sold at auction – from auction house Christie’s the day before, which he has reportedly named “Sweet Josephine”.

A model wears the 'Blue Moon' diamond during a 'Magnificent Jewels and Noble Jewels' sale from Sotheby's auction house on 11 November (AFP/Getty Images)

AFP have named the mystery buyer as property tycoon Joseph Lau, who is listed by Forbes as the sixth richest man in Hong Kong and 114th wealthiest globally.

A Hong-Kong based spokeswoman for Lau allegedly confirmed the two purchases to AFP.

David Bennet, head of Sotheby's international jewellery division, said the “Blue Moon” was “the most expensive diamond, regardless of colour, and the most expensive jewel ever sold at auction”.

The gem was locked in an eight-minute-long telephone bidding war between two bidders before it was finally sold, however the precious stone stayed within its pre-sale estimate of between $35 and $55 million.

The diamond was found in South Africa last year and was the largest cushion shaped blue stone in the fancy vivid category ever to appear at auction.

It is not the first time Mr Lau has bought rare jewels for his daughter. In 2009, he reportedly spent $9.5 million on another blue diamond, which he renamed the “Star of Josephine”.