A rare diamond called the Blue Moon sold for $43.2 million yesterday at a Sotheby’s auction in Geneva, Switzerland.

The rare gem belonged to Cora International, a diamond specialist based in the US. 

It was the centrepiece of Sotheby’s November 11 auction of Magnificent Jewels and Noble Jewels. 

Ehud Laniado, Chairman of Cora International, said: “This diamond is a true gift of nature. The GIA (Gemological Institute of America) graded 400 blue diamonds and only four of the 400 were graded fancy vivid blue. So even amongst this extremely rare class of blue diamonds, to get one vivid blue, 12 carats, internally flawless, is really as rare as a 'blue moon.'"

“For five months our experts assessed the stone. Thirty models were created, and each cut differently until the perfect result achieved,” he continues. "Afterwards, it took us three more months to bring the stone to its final spectacular shape using advanced technology and sophisticated tools. Jewellers have a chance to handle such a unique diamond once in a life time, perhaps, and we are delighted that Cora had the opportunity to have this experience." 

The Blue Moon diamond was discovered in January 2014 at the historic Cullinan mine in South Africa. Obtained by Petra diamonds as a 29.62 carat rough diamond, the stone was purchased by Cora International in February 2014 for $25.55 million in a competitive bid. 

The diamond is an outstanding vivid blue with rare saturation, tone and clarity. Blue diamonds are among the rarest and most highly coveted of all diamonds. The stone is one of the most exceptional to be found at Cullinan mine, which is considered the most important source of blue diamonds in the world. 

The Blue Moon was exhibited at the Natural History Museum of Los Angeles County (NHM), in a special temporary exhibition in the museum's Gem Vault. The diamond has also been on display in other museums.

Headquartered on Fifth Avenue in New York City, Cora is a leading luxury brand and is considered one of the world's leading firms specialising in cutting large and important diamonds. Cora is known worldwide for its rare and unique diamonds of large sizes and vivid fancy colours.