The Zoe Diamond

A diamond without a past

Most famous diamonds arrive with a paper trail of mines, cutters and royal owners. This one arrived with almost none. A 2025 trade report noted that it is unclear where the stone was recovered or exactly when it entered Bunny Mellon's jewelry collection, and an account published around its second sale said little is known of where she acquired the gem, or when she wore it. One gem writer summed it up as a diamond that more or less appeared, broke two of the most coveted records in the business and left almost nobody able to say where it came from.

What is documented is the stone itself. The Gemological Institute of America graded it a 9.75-carat pear-shaped Fancy Vivid Blue, the most saturated color grade a blue diamond can receive. A 2025 description put Fancy Vivid at less than one percent of all blue diamonds, which are themselves scarce. Reports from 2014 give its clarity as VVS2; a 2025 trade report says VVS1. The sources disagree, and this page does not settle it.

Blue diamonds take their color from trace amounts of boron caught in the crystal lattice as the stone forms, which lets the diamond absorb red and yellow light. Gem writers describe them as forming far deeper in the earth than most diamonds and as making up fewer than 0.02 percent of all diamonds. In 2014 the Mellon stone was set as a pendant.

Bunny Mellon, who wanted nothing noticed

Rachel Lowe Lambert was born in New York on August 9, 1910. Her grandfather Jordan Lambert invented Listerine, and her father, Gerard Barnes Lambert, marketed it, ran the Gillette Safety Razor Company and helped found Warner-Lambert. Her mother nicknamed her Bunny. She married Stacy Barcroft Lloyd Jr. in 1932, and after their divorce she married the banking heir, collector and horse breeder Paul Mellon on May 1, 1948.

She had no formal training as a gardener but became an authority on American horticulture and assembled one of the largest collections of rare horticultural books. In 1961 President John F. Kennedy asked her to redesign the White House Rose Garden. She later designed landscapes for Jacqueline Kennedy's home on Martha's Vineyard and the Kennedy Presidential Library, created the garden of Hubert de Givenchy's home in France and helped restore the Potager du Roi at Versailles.

Her jewelry was as deliberate as her gardens. She and Paul Mellon were the largest clients of the jeweler Fulco di Verdura, and she bought some 140 pieces by her friend Jean Schlumberger, many of them designed together. In a 1969 interview about garden design she said that "nothing should be noticed," a line often taken as her approach to life. She also said, "It is wasteful to be mediocre."

Mellon died at her home in Upperville, Virginia, on March 17, 2014, at 103. Proceeds from the sale of her collections went to the Gerard B. Lambert Foundation, which she had set up in memory of her father and which supports the Oak Spring Garden Library on the Mellon estate.

Twenty minutes in New York

In November 2014 more than 1,500 items from Mellon's collection went to auction in New York. Paintings, furniture and objects brought $158.7 million at the main sale on November 10, led by two Rothkos. More than 250 of her jewels followed on the evening of November 20 and the morning of November 21, and the blue diamond was photographed alone on the cover of the jewelry catalog.

It carried a high estimate of $15 million. Accounts of the bidding differ in detail: one report says seven bidders competed for 20 minutes; another describes two telephone bidders raising each other in $100,000 steps for 20 minutes. It sold for $32,645,000 to applause, the top price of the evening.

The result broke two records. It beat the previous auction record for a blue diamond, $24.3 million for the Wittelsbach Diamond in London in December 2008, and at $3,348,205 per carat it beat the per-carat record for any diamond, which had been nearly $2.4 million for a 14.82-carat fancy vivid orange diamond in Geneva in November 2013. The first jewelry session brought $42.1 million in all, more than double its estimate.

The buyer, first described only as a private collector from Hong Kong, named the stone the Zoe Diamond. He was later identified as Joseph Lau, the Hong Kong property developer, who said through a spokeswoman that it was for his daughter Zoe. In the same month he bought her a 10.1-carat ruby and diamond brooch for HK$65 million and called it the Zoe Red. Lau had a habit of naming stones for his children: in 2009 he paid $9.5 million for a 7.03-carat blue he called the Star of Josephine, and in 2015 he bought the 12.03-carat Blue Moon, renamed the Blue Moon of Josephine, which took the per-carat record from the Zoe. A Macau court had convicted Lau of bribery and money laundering in 2014; he avoided prison by not traveling there.

Recut, reset, and sold again

After the 2014 sale the owner had the stone retouched to improve its clarity. It went from 9.75 to 9.51 carats and was graded Internally Flawless. It was taken out of its pendant and reset in a serpentine pave diamond ring in platinum, with the words "Fancy Vivid Blue" engraved inside the shank (the engraving itself is reported to read "Fancy Vivd Blue").

In September 2025 the stone, now called the Mellon Blue, was announced for auction in Geneva with an estimate of $20 million to $30 million, less than what had been paid for it eleven years earlier. It was previewed in Hong Kong and offered on November 11, 2025. It sold for CHF 20,525,000, or $25,592,269 including fees, inside the estimate. The buyer was not disclosed.

The mood was described as cautious. One online jeweler's managing director called it "not the dazzling moment I expected," blaming geopolitical tensions, tariffs and a weaker Chinese economy for keeping usual buyers away. The 2014 record had long since fallen: the 14.62-carat Oppenheimer Blue sold for $57.5 million in Geneva in 2016, and the 15.10-carat De Beers Blue for $57.5 million in Hong Kong in April 2022. A 2025 account noted that the Zoe's 2014 price no longer ranked among the top ten.

How to tell this stone from other great blues

The shape is the first clue. Among the record-setting blues it is usually compared with, it is a pear: the Wittelsbach is cushion-shaped and the Oppenheimer Blue an elongated emerald cut. Its 2025 description calls it a modified pear brilliant-cut.

Its weight tells you which chapter you are in. As the Mellon pendant and as the Zoe Diamond at sale it was 9.75 carats with a reported VVS2 clarity grade. As the ring sold in 2025 it is 9.51 carats and Internally Flawless, set in platinum with single-cut diamonds and engraved inside the shank.

Its names change too. The same stone has been called Mrs. Mellon's diamond, the Zoe Diamond (one 2025 report says Zoe Blue) and the Mellon Blue. Reports of how old Lau's daughter was in 2014 also vary, and the sources do not agree on whether Zoe was his elder or younger daughter, so this page leaves that out.

The numbers

Carat weight

9.75 ct (2014); 9.51 ct after retouching (2025)

Color grade

Fancy Vivid Blue, natural color (GIA)

Clarity

VVS2 as reported in 2014 (one 2025 report says VVS1); Internally Flawless after recutting

Shape

Pear; described in 2025 as a modified pear brilliant-cut

Origin mine

Not documented

Cutter

Not documented, for the original cut or the later retouching

Setting

Pendant (2014); serpentine pave ring in platinum with single-cut diamonds (2025)

Price per carat, 2014

$3,348,205, then a record for any diamond

Timeline

1. Aug 9, 1910

   Rachel Lowe Lambert, later Bunny Mellon, is born in New York.

2. May 1, 1948

   She marries Paul Mellon.

3. 1961

   President Kennedy asks her to redesign the White House Rose Garden.

4. Dec 2008

   The Wittelsbach Diamond sells for $24.3 million in London, the blue-diamond auction record the Mellon stone would later break.

5. Mar 17, 2014

   Bunny Mellon dies at 103 at her home in Upperville, Virginia.

6. Nov 10, 2014

   The main sale of her collection brings $158.7 million in New York.

7. Nov 20, 2014

   The 9.75-carat blue sells for $32,645,000 at auction in New York, setting two world records; the Hong Kong buyer names it the Zoe Diamond.

8. 2015

   Joseph Lau buys the 12.03-carat Blue Moon, which takes the per-carat record from the Zoe.

9. 2016

   The Oppenheimer Blue sells for $57.5 million in Geneva, a new high for a blue diamond.

10. Apr 2022

    The 15.10-carat De Beers Blue sells for $57.5 million in Hong Kong.

11. Sep 2025

    The recut 9.51-carat stone, now called the Mellon Blue, is announced for sale in Geneva with a $20 million to $30 million estimate.

12. Nov 7, 2025

    The stone is shown at a public preview in Geneva.

13. Nov 11, 2025

    It sells for CHF 20,525,000 ($25,592,269 with fees) at auction in Geneva.

The world in 2014

• Mar 8, 2014

  Malaysia Airlines Flight 370 disappears with 239 people on board.

• Mar 21, 2014

  Russia formally annexes Crimea.

• Jun 29, 2014

  The Islamic State of Iraq and the Levant declares itself a caliphate.

• Jul 13, 2014

  Germany beats Argentina 1-0 to win the World Cup in Brazil.

• Nov 3, 2014

  One World Trade Center opens in New York.

• Nov 12, 2014

  The Philae probe lands on Comet 67P, the first landing on a comet.

Price record

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 Zoe Diamond is number 13 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 (12 here) is editorial: how much an object defines its field, not price alone.

Did you know

• The diamond's price in 2014 was more than double its high estimate of $15 million.
• At $3,348,205 per carat in 2014, it set the record for price per carat for any diamond of any color.
• After the sale the owner had it retouched for clarity, trimming it from 9.75 to 9.51 carats.
• Its 2025 ring is engraved inside the shank, and the engraving is reported to read "Fancy Vivd Blue."
• The same buyer named three record-setting stones for his daughters within six years: the Star of Josephine, the Zoe Diamond and the Blue Moon of Josephine.
• In 2014 the stone appeared by itself on the cover of the catalog for Bunny Mellon's jewelry sale.
• Bunny Mellon's grandfather invented Listerine.
• It sold for about $7 million less in 2025 than in 2014, even after being upgraded to Internally Flawless.