FLOAT 100 · Jewelry · No. 6
The Blue Moon of Josephine
A blue crystal pulled from a South African mine in January 2014 was cut to just 12.03 carats, glows red after ultraviolet light, and less than two years later became the most expensive jewel ever sold at auction, renamed that night for a seven-year-old girl in Hong Kong.
- Year
- sold 2015
- By price in jewelry
- 6 of 100
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Create a free account- Found
- January 2014, Cullinan mine, South Africa, as a 29.62-carat rough crystal
- Weight
- 12.03 carats, cushion modified brilliant
- Grade
- Fancy Vivid Blue, Internally Flawless (GIA)
- Measurements
- 15.57 x 13.47 x 7.55 mm
- Type
- IIb; its color comes from trace boron, measured at about 0.26 parts per million
- Phosphorescence
- Orange-red glow visible for up to about 20 seconds after ultraviolet exposure
- Cut by
- Cora International, New York, which bought the rough for $25.6 million in February 2014
- First shown
- Natural History Museum of Los Angeles County, September 13, 2014 to January 6, 2015
- Sold
- November 11, 2015, at auction in Geneva, for 48.6 million Swiss francs with fees (about $48.4 million)
- Owner
- Hong Kong property developer Joseph Lau, who renamed it for his daughter Josephine
A blue from the Cullinan pipe
The stone that became the Blue Moon of Josephine was recovered in January 2014 at the Cullinan mine in South Africa, then operated by Petra Diamonds. The rough crystal weighed 29.62 carats, usually rounded to 29.6.
Cullinan sits on what the stone's auction catalog called the second-largest kimberlite pipe by inherent value, and it has a long record of rare blue diamonds. Even there, blues are scarce: the same catalog notes that less than 0.1 percent of diamonds recovered showed any evidence of blue color. A trade report on the 2014 rough sale describes the mine as the source of the two main diamonds in the British Crown Jewels and the world's most important source of very rare blue diamonds.
Petra had sold other large blues from the mine since buying it in June 2008, including a 26.6-carat blue rough for $9.5 million in 2009 and a 25.5-carat blue for $16.9 million in 2013. The January 2014 stone outsold them all.
Buying the rough and cutting the moon
On February 13, 2014, Petra sold the rough for $25.6 million, or $862,780 per carat, after what the company called a highly competitive sales process. The buyer was Golden Yellow Diamonds acting for Cora International, a New York diamond company. Petra's chief executive, Johan Dippenaar, said the result affirmed the stone "as one of the most important blue diamonds ever recovered." The Gemological Institute of America later described the figure as a record price per carat for rough.
Cora fashioned the crystal into a single cushion modified brilliant of 12.03 carats, keeping roughly 40.6 percent of the rough weight. The GIA dates completion of the polished stone to June 2014. Accounts of how long the work took differ: one report says cutting and polishing took six months, while another says experts studied the rough for five months and a master cutter then needed three months to cut and polish it.
The name came before the buyer. The stone was presented as the Blue Moon Diamond; one account explains that the cushion's rounded proportions evoke the shape of a full moon. Cora's chairman, Ehud Laniado, later stressed its rarity, noting that of 400 blue diamonds the GIA had graded, only four were Fancy Vivid blue.
What the laboratory found
The GIA graded the polished stone Fancy Vivid Blue, the top of the scale, and Internally Flawless, under report number 1162555606. It measures 15.57 by 13.47 by 7.55 millimeters. In a GIA study of 462 blue diamonds cited in the auction catalog, only about 1 percent reached a Fancy Vivid grade.
The Blue Moon is a type IIb diamond, the class colored by boron. A study in the GIA journal Gems & Gemology in winter 2014, by Eloïse Gaillou, Jeffrey E. Post, Keal S. Byrne and James E. Butler, measured its uncompensated boron at 0.26 parts per million, within the range of the Hope (0.36), the Wittelsbach-Graff (0.19) and the Blue Heart (0.24). The auction catalog puts it more simply: fewer than one boron atom per million carbon atoms.
Its most distinctive trait shows up in the dark. After exposure to ultraviolet light, especially short-wave, the stone glows orange-red for up to about 20 seconds, while most blue diamonds give a short bluish phosphorescence. The GIA study traced the glow to an unusually strong emission band at 660 nanometers, a trait found in only a minority of type IIb diamonds and previously uncommon in stones from Cullinan.
Identifying features, then: 12.03 carats, cushion shape, the dimensions above, a Fancy Vivid Blue Internally Flawless grade and that red afterglow. It was offered set in a platinum ring.
From a museum vault to a record in Geneva
The Blue Moon made its first public appearance at the Natural History Museum of Los Angeles County, on view from September 13, 2014, to January 6, 2015, kept behind giant steel doors. Suzette Gomes, Cora's chief executive, told a Los Angeles station: "It's a very special vivid blue, and then it's internally flawless, that's important to us."
On November 11, 2015, the stone was offered at auction in Geneva with an estimate of 34.2 million to 53.7 million Swiss francs, reported in dollars as $35 million to $55 million. After a telephone bidding war of about eight minutes, the hammer fell at 43.2 million francs; with fees the price was 48.6 million francs, about $48.4 million. Reports differ slightly on the dollar figure, with some giving $48.5 million. The price per carat was about 4.02 million francs, more than $4 million.
The buyer was Joseph Lau Luen-hung, a Hong Kong property developer, who renamed the stone the Blue Moon of Josephine after his seven-year-old daughter. The night before, at another Geneva sale, he had paid about $28.5 million for a 16.08-carat vivid pink diamond and renamed it Sweet Josephine. In 2009 he had bought a blue diamond for $9.5 million and named it the Star of Josephine.
The purchases came with a shadow. CBS News reported that a Macau court had convicted Lau in 2014 of bribery and money laundering and sentenced him to more than five years in prison, a sentence he avoided by staying out of Macau.
Records and what they mean
The auctioneer called the result a set of records: the most expensive diamond regardless of color, the most expensive jewel ever sold at auction, and the highest price per carat for any diamond or gemstone. It displaced the Graff Pink, which had sold for $46.2 million in Geneva in November 2010. "I have never seen a more beautiful stone. The shape, the color, the purity - it's a magical stone," said the auctioneer, David Bennett.
The arc from rough to auction is unusually well documented: $25.6 million for the rough in February 2014, a 12.03-carat polished stone by June, a museum debut in September, a peer-reviewed laboratory study that winter, and a $48.4 million sale in November 2015. Few celebrated diamonds have every step on the public record within two years of leaving the ground.
The numbers
- Carat weight
- 12.03 carats (cut from 29.62-carat rough)
- Color and clarity
- Fancy Vivid Blue, Internally Flawless (GIA report 1162555606)
- Diamond type
- IIb, boron about 0.26 ppm
- Origin mine
- Cullinan mine, South Africa
- Cutter
- Cora International, New York
- Shape and size
- Cushion modified brilliant, 15.57 x 13.47 x 7.55 mm
Timeline
Petra Diamonds acquires the Cullinan mine in South Africa.
Joseph Lau buys a blue diamond for $9.5 million and names it the Star of Josephine.
A 29.62-carat blue rough crystal is recovered at Cullinan.
The rough sells for $25.6 million ($862,780 per carat) to Golden Yellow Diamonds for Cora International.
Cutting is completed: a 12.03-carat cushion modified brilliant, graded Fancy Vivid Blue, Internally Flawless.
The Blue Moon Diamond goes on public view for the first time, at the Natural History Museum of Los Angeles County.
Gems & Gemology publishes a GIA study of the stone in its winter issue.
The Los Angeles exhibition closes.
Lau buys the 16.08-carat Sweet Josephine pink diamond in Geneva for about $28.5 million.
The Blue Moon sells at auction in Geneva for 48.6 million Swiss francs with fees, about $48.4 million, a record for any jewel at auction.
Lau renames it the Blue Moon of Josephine, for his seven-year-old daughter.
The world in 2015
The Swiss National Bank abandons its cap on the franc against the euro, shaking international markets.
A magnitude 7.8 earthquake strikes Nepal.
NASA's New Horizons makes the first close flyby of Pluto.
Cuba and the United States restore full diplomatic relations.
Volkswagen is implicated in rigging diesel emissions tests on about 11 million vehicles.
Coordinated attacks strike Paris, two days after the Geneva sale.
The Paris Agreement on climate is finalized at COP21.
Price record
| Date | Price | Kind |
|---|---|---|
| Feb 13, 2014 | $25,600,000 | Private saleThe 29.6-carat rough crystal, before cutting, sold by the mine operator; $862,780 per carat. |
| Nov 11, 2015 | $35,000,000 | Estimate, not a saleLow end of the pre-sale estimate of $35 million to $55 million (34.2 million to 53.7 million Swiss francs). |
| Nov 11, 2015 | $48,400,000 | Sold at auctionSold at auction in Geneva. Hammer 43.2 million Swiss francs; 48.6 million francs with fees. Some reports give $48.5 million. |
A realized auction price is what a buyer actually paid on the date shown, including the buyer's premium where the sale reported it. It is the strongest kind of reference price, and it is a record of one sale of one object on one day, not a promise of what the next example will bring.
By reference price, The Blue Moon of Josephine is number 6 of 100 in the jewelry entries of the FLOAT 100. 44 of those 100 rest on a realized sale; the rest carry an asking price or a guide value, and each page says which. Rank within the FLOAT 100 itself (6 here) is editorial: how much an object defines its field, not price alone.
Did you know
- The stone kept only about 40.6 percent of its rough weight when it was cut.
- After ultraviolet light it glows orange-red for up to about 20 seconds; most blue diamonds glow briefly blue.
- Its boron content falls in the same range as the Hope diamond's.
- In one GIA study of 462 blue diamonds, only about 1 percent were graded Fancy Vivid.
- Its buyer had bought a pink diamond for the same daughter the night before and renamed it Sweet Josephine.
- The hammer fell after a telephone bidding war of about eight minutes.
How this page is made
- The figure
- One reference price, shown with its own kind. FLOAT does not average it with anything or adjust it for time.
- Realized or not
- A realized price is a completed sale. An asking price, an estimate and a price-guide value are not sales, and are labeled as such wherever they appear.
- The story
- Researched from published records and checked fact by fact. Updated Oct 1, 2026.
- Archive
- Oct 5, 2026