The Aga Khan Emerald Brooch

A green stone from Muzo

The center of this jewel is a single square emerald of about 37 carats from Colombia. A 2024 auction essay traced it to Muzo, an emerald mine about 60 miles north of present-day Bogotá that was worked for at least five centuries before the Spanish arrived in the Americas. Muzo is the source of some of the most famous emeralds in history, including the Devonshire, an uncut crystal of 1,383.95 carats that the 6th Duke of Devonshire acquired from Emperor Dom Pedro I of Brazil around 1831. Since the colonial era, Muzo stones have been prized for an intense green color and high transparency.

Two gem laboratories examined the stone before its 2024 sale. One, in 2023, weighed it at 37.00 carats, of Colombian origin, with no indications of clarity enhancement. The other, a Swiss laboratory, in 2024 weighed it at 37.003 carats, also Colombian, with no indications of clarity modification in its fissures, and added an appendix letter attesting to its exceptional quality and rarity. That finding matters because most emeralds contain natural inclusions and surface-reaching fissures, which are routinely filled with oils or polymers to improve their look. A specialist at the 2024 sale called a stone of this size with no sign of enhancement extraordinary.

The shape is unusual too. The emerald is cut extremely thin and flat, which, the same specialist said, makes it look like a 50-carat stone. Flat emeralds tend to lose color at the center, but this one stays an even green across the whole face.

A prince, a model and Cartier

Nina Dyer was born in British Ceylon (now Sri Lanka) on February 15, 1930, and grew up on a tea plantation. She moved to England at about 20, modeled swimwear in London and then moved to Paris, where she became a favorite model of the couturier Pierre Balmain. In June 1954 she married Baron Hans Heinrich Thyssen-Bornemisza, heir to the Thyssen industrial fortune. Before the wedding he had given her cars, jewels and two pet black panthers, and on one Valentine's Day an island in Jamaica. They divorced in 1956.

On August 27, 1957, at the family's house at Collonges-Bellerive near Geneva, she married Prince Sadruddin Aga Khan, a son of Sultan Mahomed Shah, Aga Khan III, the hereditary Imam of the Ismaili Muslims. Sadruddin, born in 1933 and a 1954 Harvard graduate, would go on to serve as United Nations High Commissioner for Refugees from 1966 to 1977. During the marriage he gave Dyer sports cars, a second Jamaican island and jewels from Cartier, Mappin & Webb and Harry Winston.

In 1960 he commissioned this brooch from Cartier in Paris. The sale catalog of 1969 described it as a superb square-cut emerald in a border of twenty navette-cut diamonds forming a fancy lozenge-shaped cluster. Dyer, according to the auction house that sold it in 2024, wore it to numerous prominent events. The couple divorced in 1962. Dyer died in Paris on July 3, 1965, at the age of 35.

May 1, 1969: the sale that opened Geneva

Dyer's jewels were offered on May 1, 1969, at the Hotel Richemond in Geneva, as the headline property of the first jewelry auction an international auction house had ever held in Switzerland. The house had opened its Geneva office only six months earlier. Swiss banks were booming and few tariffs applied to jewelry sales, which made the city a natural center for the trade. Representatives of Boucheron, Bulgari, Cartier, Chaumet and Harry Winston came, along with collectors from across Europe.

Accounts of the sale's size differ: one says Dyer's jewels were 45 of 108 lots, another that most of the more than 40 lots were hers. A jewelry specialist who was 21 at the time and attended with his father later recalled that bids came from all over the room and some lots took more than five minutes to sell. The sale totaled more than CHF 12.7 million.

The emerald brooch was among the top lots and went to Van Cleef & Arpels. The figure given for it differs by source: the auction house's own 2024 account says CHF 900,000, while a 2024 trade report says Van Cleef & Arpels paid $75,000, and adds that the brooch sold for double its estimate. The same report says the sale benefited animal welfare causes in Africa, Asia and Europe, as Dyer's will directed.

Three great jewelers, then a record

A few years after the 1969 sale, the brooch passed from Van Cleef & Arpels to Harry Winston, the New York jeweler nicknamed the King of Diamonds, who modified it so it could also be worn as a pendant. The 2024 catalog notes that it appears in H. Nadelhoffer's 1984 book on Cartier and in L. Krashes's 1988 book on Harry Winston. A specialist summed up its path: it had passed through the hands of three of the greatest jewelers in the world.

It came back to auction in Geneva on November 12, 2024, at the Four Seasons Hotel des Bergues, 55 years after its first sale, as lot 100. The estimate was CHF 5.2 million to 7 million, reported in U.S. terms as $6 million to $8 million. Bidders had to obtain a special high-value paddle to compete. It sold for CHF 7,765,000 including fees, given as US$8,859,865. The specialist who had watched the 1969 sale as a young man handled the winning telephone bidder.

The result made it the most expensive emerald ever sold at auction, taking that title from Elizabeth Taylor's Bulgari emerald brooch, which had sold for about $6.5 million in 2011. On a per-carat basis it did not beat the Rockefeller Emerald: a 2024 trade report worked the Aga Khan stone out at about $237,838 per carat, against about $305,000 per carat for the 18.04-carat Rockefeller stone in 2017. The full sale totaled $54.7 million, with buyers from 37 countries.

How to recognize it

The design is simple and distinctive: one large, flat, square emerald, framed by a single row of 20 marquise-shaped diamonds whose points form a lozenge, or diamond-shaped, outline. The mount is platinum and 18k yellow gold with French marks. The jewel stands 4.9 cm high. It is unsigned, and its number is recorded as indistinct.

Its documentation includes a 2023 laboratory report, no. 23112014, at 37.00 carats, and a 2024 report, no. 136623, at 37.003 carats, both stating Colombian origin and no clarity enhancement. The diamonds total approximately 12.04 carats. The 1969 catalog gave the emerald as approximately 37.41 carats, a different figure from the modern laboratory weights.

The numbers

Carat weight

37.00 carats (2023 laboratory report); 37.003 carats (2024 laboratory report); approximately 37.41 carats in the 1969 catalog

Color and clarity

No color grade published; described as an even green with high transparency; both laboratory reports found no clarity enhancement

Origin mine

Muzo, Colombia, per the 2024 sale essay; the laboratory reports state Colombia

Cutter

Not recorded in the sources consulted

Cut

Square, cut unusually thin and flat

Diamonds

20 marquise-shaped diamonds, approximately 12.04 carats total

Setting

Platinum and 18k yellow gold, Cartier Paris, 1960; 4.9 cm high

Timeline

1. Feb 15, 1930

   Nina Dyer is born in British Ceylon.

2. Jan 17, 1933

   Prince Sadruddin Aga Khan is born at Neuilly-sur-Seine, France.

3. Jun 23, 1954

   Dyer marries Baron Hans Heinrich Thyssen-Bornemisza in Colombo; they divorce in 1956.

4. Aug 27, 1957

   Dyer marries Prince Sadruddin Aga Khan near Geneva and takes the name Princess Nina Aga Khan.

5. 1960

   Prince Sadruddin commissions the emerald and diamond brooch from Cartier, Paris, for Dyer.

6. 1962

   Dyer and Prince Sadruddin divorce.

7. Jul 3, 1965

   Nina Dyer dies in Paris at 35.

8. May 1, 1969

   The brooch is sold at auction at the Hotel Richemond in Geneva, in the first jewelry auction an international house held in Switzerland; Van Cleef & Arpels buys it.

9. 1984

   The brooch is illustrated in H. Nadelhoffer's book on Cartier.

10. 1988

    The brooch is cited in L. Krashes's book on Harry Winston, the jeweler that had acquired it and adapted it as a pendant.

11. 2023

    A gem laboratory weighs the emerald at 37.00 carats, Colombian, with no indications of clarity enhancement.

12. 2024

    A Swiss laboratory weighs it at 37.003 carats and issues a letter attesting to its exceptional quality and rarity.

13. Nov 12, 2024

    The brooch sells at auction in Geneva for CHF 7,765,000 (US$8,859,865), a world auction record for an emerald.

The world in 1960

• Mar 22, 1960

  Arthur Schawlow and Charles Townes receive the first patent for a laser in the United States.

• Apr 21, 1960

  Brazil moves its capital from Rio de Janeiro to the newly built city of Brasília.

• May 1, 1960

  The Soviet Union shoots down an American U-2 spy plane and captures its pilot, Francis Gary Powers.

• May 22, 1960

  The 9.5 magnitude Valdivia earthquake strikes Chile, the most powerful earthquake on record.

• Aug 25, 1960

  The Summer Olympic Games open in Rome.

• Oct 1, 1960

  Nigeria becomes independent from the United Kingdom.

• Nov 8, 1960

  John F. Kennedy is elected President of the United States.

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 Aga Khan Emerald Brooch is number 22 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 (23 here) is editorial: how much an object defines its field, not price alone.

Did you know

• Because the stone is cut so thin and flat, it looks like a 50-carat emerald, though it weighs about 37.
• Nina Dyer's first husband gave her two pet black panthers and an island in Jamaica; her second gave her another Jamaican island next to it.
• Earlier in 2024, another of Dyer's Cartier commissions, a 1962 "Black Alley Cat" brooch, also went to auction; she was known for her love of cats.
• The jewelry specialist who handled the winning telephone bid in 2024 had attended the brooch's first sale in 1969 at 21, fresh out of gemology school.
• Bidders in 2024 had to obtain a special high-value paddle just to bid on it.
• It holds the record for the highest total price for an emerald at auction, but not the per-carat record, which still belongs to the Rockefeller Emerald.