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Blue Moon Diamond Sells For $48.5m, Smashing All-time Price Record At Sotheby's Geneva

The much-ballyhooed Blue Moon diamond set an all-time record for the highest price ever paid at auction for a gemstone when an anonymous Hong Kong bidder captured the coveted 12.03-carat gem for a jaw-dropping $48.5 million at Sotheby's Geneva.

The buyer renamed the stone "The Blue Moon of Josephine," which was curious, because only one day earlier at Christie's Geneva, an unnamed Hong Kong bidder paid $28.5 million for a pink diamond and named it "Sweet Josephine." The Associated Press later reported that the unnamed buyer of both gems was, in fact, Hong Kong billionaire Joseph Lau, who has a young daughter named Josephine.


The internally flawless, fancy vivid blue diamond — originally named "Blue Moon" for the fact that a specimen of this size, color and clarity comes around only once in a blue moon — beat out the 24.68-carat, $46.15 million Graff Pink, which had held the "highest price" title since 2010.


When the hammer went down on the final lot at Sotheby's Magnificent Jewels and Noble Jewels sale yesterday, the cushion-shaped Blue Moon had also smashed the auction record for the highest price ever paid per carat for any gemstone. The previous mark, established by the vivid blue 9.75-carat Zoe Diamond in November 2014 at $3.3 million per carat, was obliterated by the Blue Moon, which achieved $4.02 million per carat.

The Blue Moon's selling price was in the upper-middle range of Sotheby's pre-sale estimate of $35 million to $55 million.


Only a day earlier at rival Christie's Geneva, a rare cushion-shaped 16.08-carat pink diamond sold for $28.5 million ($1.7 million per carat), setting an auction record for any vivid pink diamond. The gem's selling price slightly exceeded the auction house's estimate of $23 million to $28 million. The winning bid was placed by a private Hong collector, who has since been identified as billionaire Lau.

But the biggest news coming out of Geneva was the record-breaking sale of the Blue Moon. Among the largest known fancy vivid blue diamonds, the Blue Moon demonstrates the highest possible color grading for blue diamonds. A GIA Monograph grading report described the hue of the diamond as “likely to have never before been seen within such a large diamond, or any gemstone.”

"For me the Blue Moon was always the blue diamond of my career," said David Bennett, worldwide chairman of Sotheby’s International Jewelry Division. "I've never seen a more beautiful stone – its shape, color and purity. It's a magical stone."


Unearthed in January by Petra Diamonds Ltd. at its legendary Cullinan mine in South Africa, the 29.6-carat rough was heralded at the time as “one of the most important blue diamonds ever recovered” by Petra chief executive Johan Dippenaar. In February, luxury jeweler Cora International purchased the rough gem for $25.6 million. Six months later, the company unveiled its 12.03-carat internally flawless cushion-cut blue masterpiece.

Blue diamonds get their color from trace amounts of boron in their chemical makeup. Colorless diamonds, by comparison, are pure carbon with no trace elements.