The Cullinan Blue is expected to fetch more than $45 million ($62.45 million). Experts believe it is the largest and one of only five blue diamonds over 10 carats going through the auction process.
The diamond will be the solo centrepiece of Sotheby's luxury week in Hong Kong. The Gemological Institute of America (GIA) has classified it as an internally flawless Type IIb. That is, the highest colour classification category to date.
According to Bruce Cleaver, CEO of the De Beers Group, “this diamond is one of the best De Beers has ever seen. It is extremely rare and unique, and as the home of diamonds, De Beers is delighted to partner with Sotheby's to bring this diamond to the world.”.
UK-based Petra Diamonds discovered the diamond in April 2021 at the Cullinan mines in South Africa. Later, in a special auction, De Beers and diamond producer Diacore bought it for $40.2 million ($55.79 million).
A 39.35 carat rough blue diamond is the origin of the graded-cut stone.
Petra sold it to DeBeers and Diacore three months after it was revealed. They then cut it up and shot it at Cullinan Blue.
Since then, the diamond has been shown in exhibitions in New York, London, Dubai, China and Taiwan.
Industry expectations are high for the auction. Specifically, they anticipate the sale price to be in excess of $50-60 million ($69.39-83.26 million).
It is larger than the 14.62-carat Oppenheimer Blue, which Christie's-Geneva sold in May 2016 for $57.5 million (79.79 million $AU); and the 12.03-carat Blue Moon, which was auctioned in 2015 by Sotheby's for $48.5 million (67.31 million $AU).
It is worth noting that Oppenheimer Blue currently holds the record for the largest blue diamond sold at auction.
On the other hand, Blue Moon holds the record for the most expensive blue diamond in terms of carat value. Its value exceeds $4 million ($5.55 million AAA) per carat.
Blue Moon was purchased by Sotheby's from the Hong Kong billionaire. They then renamed it Blue Moon of Josephine, in honour of the new owner's young daughter.
The largest blue diamond to date is the 20.46 carat Okavango blue diamond. It is one of the most exciting and rarest colored diamonds in existence, they claim.
It is currently in the collection of the American Museum of Natural History. The stone is about the size of a fat almond. Its origins go back millions of years and hundreds of kilometres beneath the earth's surface.
It was the Orapa mine in Botswana that revealed the oval-shaped stone in 2018. It was then given a VVS1 clarity grade for its near-perfect condition and was cut from a 41.11-carat rough diamond.
Most diamond formation reaches about 160 to 240 kilometres below the surface. For example, Okavango Blue may have formed over millions of years in the transition zone. About 640 kilometres below - through a geological process called subduction.
In line with the growing popularity of blue diamonds, Kunming Diamonds purchased the entire Argyle blue and violet diamond collection. The purchase was made at the final Argyle auction in October 2021. The total value was 24.88 carats and aptly titled “Once in a Blue Moon”.
