Cullinan Blue: Closest Thing to a World Beater
April 28, 22Sotheby's were no doubt delighted with the sale. Auction premiums added up to HK$60.9m - or $7.76m. But it must have been frustrated that it couldn't headline its press release with "Highest price ever achieved for a blue diamond". Instead they settled for "Among the highest prices ever achieved for any diamond sold at auction". Incidentally, the highest auction price paid for any diamond, ever, was $71,175,926, for a 59.60-carat IF fancy vivid pink diamond. It was sold by Sotheby's Hong Kong in April 2017 to the Hong Kong jeweler Chow Tai Fook, who named it the CTF Pink Star.
Four bidders went head-to-head yesterday for the Cullinan Blue. The anonymous winner was represented by Wenhao Yu, Chairman of Jewellery and Watches at Sotheby's Asia over the phone. Blue diamonds are flukes of nature, caused by trace amounts of boron in their crystal lattice. Only five 10ct+ blue diamonds have come to auction, and the Cullinan Blue is the first ever 15ct+. It was recovered in April 2021 by UK-based Petra Diamonds at The Cullinan mine, South Africa, the deposit it acquired from De Beers in 2008. The 39.34-carat rough gem was sold at a special tender three months later for an up-front cash payment of $40.2m to a partnership between De Beers and Diacore - equivalent to $1,021,357 per rough carat. By the time the hammer fell at Sotheby's its value had risen to $3,805,561 per polished carat.
So what has the anonymous buyer got for their money? The GIA (Gemological Institute of America) says it's the most significant internally flawless step-cut vivid blue diamond it's ever graded. It received the highest possible grading - fancy vivid blue - which is awarded to fewer than one per cent of the blue diamonds it grades. The cut-cornered rectangular step cut gem had very good polish, good symmetry and no fluorescence.
But it doesn't quite get full marks under more rigorous scrutiny. The non-profit New York-based Fancy Color Research Foundation, which provides insights, tools and services to industry professionals, gave it a score of nine out of 12 for visual in a more detailed assessment. "We use 1, 2, 3, 4, and 4+ to grade the three visual elements that GIA is silent about, although they impact the value dramatically," it says.
The Cullinan Blue was given a 3 for inner grade hue, which refers to the strength of color within each GIA saturation category. It scored just 2 for color dispersion, which relates to how well the color of a fancy color diamond is dispersed in the face-up view of a regardless as to whether the GIA grades the stone as even. And it received a 4 for undertone, which refers to a subtle hue influence in the body color of the stone. A 4 means it has no gray influence and is close to a primary blue. I'm guessing however that neither these niggles, nor the narrow miss on a world record, will take the shine off this beauty in the eyes on its new owner, whoever they are.
Have a fabulous weekend.