Vivid blue in colour and weighing 12.03 carats, it went for the “highest price per carat” ever obtained for any kind of stone, according to Sotheby’s auctioneer David Bennett.
Although Sotheby's did not reveal the gem's new owner, it has since been confirmed that Hong Kong billionaire Joseph Lau bought it for his seven-year-old daughter (lucky girl).
But before the Blue Moon came along, which diamonds brought in the highest bids in auction history? Here are the top ones.
THE GRAFF PINK
In 2010, this bright pink, 24.78 carat diamond was placed in a platinum ring and sold by Sotheby's for $46.2m at an auction in Geneva.
The purchaser was English jeweller Laurence Graff, and before that it was owned by American jeweller Harry Winston for 60 years. Until the Blue Moon came along, this diamond held the title of most expensive diamond ever sold at auction.
Sold by Christie's to an anonymous buyer in 2013, the pale pink diamond picked up $39.3m at an auction in New York. The 34.65 carat gem used to belong to an Indian prince in Hyderabad hundreds of years ago, but was given the name “princie” in the 1960s. It was discovered around 300 years ago in the Golconda mines.
The royal stone was bought by Laurance Graff from Christie's in 2008 for $24.3m. Deep blue in colour and weighing 31.06 carats, Spanish king Philip IV gave it as part of his daughter's dowry in the 17th century.
THE PERFECT PINK
In 2010, Christie's sold the bright pink diamond to an anonymous buyer in Hong Kong for $23.2m. Weighing 14.23 carats, it was first discovered in India, just like the Princie.
THE ARCHDUKE JOSEPH
While there have been big sales of coloured diamonds, clear diamonds have failed to make such a mark in auction houses. However, in 2012 this gem was sold by Christie's to an anonymous buyer for $21.4m, breaking the record for clear-cut diamonds.
The 76.02 carat diamond was named after the Austria’s Archduke Joseph August, the great grandson of a French King.
IN THE PIPELINE: THE PINK STAR
While the figures might sound impressive, there's something even more expense than the pipeline. The “Pink Star”, which is currently sitting in Sotheby's inventory, was put up for auction at $83.2m in 2013.
It wasn't sold that time because the buyer defaulted on their payment. But once a purchase goes ahead, it will no doubt smash all diamond records set to date.