The Astonishing Allnatt Diamond (Almost) Sells at Sotheby’s

Last week, as we were marveling at the royal jewels worn by the Danish and Norwegian royals during King Frederik and Queen Mary’s state visit to Oslo, the auctioneers at Sotheby’s in Geneva were busy presenting a slate of treasures to potential buyers. The auction was supposed to include a remarkable yellow diamond in a Cartier brooch setting, but at the last minute, it was pulled from the sale. Today, we’ve got a closer look at the history of the Allnatt Diamond–and its sudden disappearance from the auction block.

Sotheby’s heavily advertised the Allnatt Diamond, a remarkable 101.29 diamond with a notable golden yellow hue, as the marquee item in its May 14 Magnificent Jewels auction in Geneva. The exact provenance of the magnificent gemstone isn’t known, but Sotheby’s offered a few suggestions about its origin in their catalogue for the auction. The most likely source for the diamond, they believe, is the De Beers Millennium Mine in South Africa. That’s because “South African deposits are rich in nitrogen,” Sotheby’s explains, and so “they have yielded the vast majority of the world’s most important yellow diamonds.”

Exactly when the diamond was mined is also uncertain. The first significant yellow diamonds were found in South African mines in the 1860s. The catalogue guesses that the style and technique used to cut the Allnatt Diamond probably dates its discovery to “the late 19th or early 20th century.”

There’s no documented record of the diamond’s ownership until the 1950s. In the early years of that decade, the gem was purchased by a British art collector, Major Alfred Ernest Allnatt, whose name it still bears today. Allnatt was a fascinating figure. The son of a shopkeeper from Berkshire, he served with the Special Reserve Battalion of the Royal Inniskilling Fusiliers during World War I. He married after the war and had three children, and as his family grew he also built a business empire that included real estate holdings and a confectionary company.

Allnatt used his wealth both to enrich himself and to benefit others. In the 1940s, he was an enthusiastic racing owner, and later on he became a collector of prominent artworks. His most important art acquisition was probably The Adoration of the Magi by Rubens. He subsequently donated the painting to King’s College, Cambridge, where it hangs in the college’s chapel today. He also donated several paintings, including Caravaggio’s Salome with the Head of John the Baptist, to the National Gallery in London and gave El Greco’s Saint James the Greater to New College, Oxford in 1962.

Widowed in 1958, Allnatt married again in 1960. After his death in 1969, the extent of Allnatt’s charitable work was finally revealed to the public. Along with his patronage of the arts, he also funded the preservation of historic buildings and donated significant amounts toward the upkeep of almshouses in Oxfordshire.

When Allnatt died in 1969, a memorial service was held for him at King’s College Chapel underneath the Rubens painting that he had donated. Along with family members, representatives from numerous charities, as well as the National Gallery and the National Trust, attended the memorial. Among the pieces that apparently remained in his collection at his death was the Allnatt Diamond, acquired during his first marriage.

The diamond, which was 102.07 carats when Allnatt purchased it, was unmounted when it arrived in his collection. In 1952, he asked the artisans at Cartier in London to set the diamond in a brooch. Sketches were produced, and by the autumn of 1953, the firm had completed the piece, described by Sotheby’s as “a flowerhead composed of openwork, brilliant-cut diamond-set petals enhanced with baguette diamonds.”

In the auction press handout information, Sotheby’s also provided this view of the back of the Cartier brooch setting, showing details on how the piece is attached to the wearer’s clothing.

If the Allnatt Diamond Brooch looks a little bit familiar, there’s a good reason. The brooch was designed and made at Cartier in London at the same time that the firm was busy with another important commission: the brooch setting for Queen Elizabeth II’s Williamson Pink Diamond. In some ways, the Allnatt brooch is like the little sister of the Williamson Pink Diamond Brooch. The five petals with curling edges, the central colored diamond, the baguette diamond stem–they’re definitely part of the same general design vision coming out of the Cartier atelier in London in the early ’50s. We most recently saw the Williamson Pink Diamond Brooch sparkling on Queen Camilla at a Buckingham Palace garden party.

Just like its provenance, the chain of ownership of the Allnatt Diamond isn’t particularly clear. It popped up next in public in 1996, when it was sold at auction in Geneva. The lot notes from that sale attributed its ownership simply to “a Lady.” The diamond sold for a whopping $3,043,496 USD during that auction. At the time, it still weighed in at 102.07 with a Fancy Intense Yellow grade. The new owners of the diamond decided to make a small revision to the stone. It was recut ever so slightly, producing a gem that weighed 101.29 carats. The changes also enhanced the color of the gem, and the GIA upgraded their assessment, grading it a Fancy Vivid Yellow diamond.

Who were those new owners? It’s not particularly clear. At some point between 1996 and the present day, the stone belonged to the Siba Corporation, which is based in Hong Kong. The company was founded by a man named Sam Abram, who was a diamond merchant and an avid collector of colored diamonds. Abram, who passed away in 2019, made frequent high-dollar gemstone purchases from auctions, especially in the 1980s and 1990s. The Allnatt Diamond was certainly part of his company’s collection by 2003, when it was loaned out for a special exhibition.

In the summer of 2003, the Allnatt Diamond was included in a landmark exhibition at the Smithsonian’s National Museum of Natural History in Washington, D.C. “The Splendor of Diamonds” gathered together a rainbow of some of the world’s most impressive colored diamonds. This photograph from the Smithsonian shows off some of the diamonds on display. At the top of the photo is the gargantuan pear-shaped De Beers Millennium Star (203.04 ct). Below that diamond, from left to right, are the Steinmetz Pink (59.60ct, now known as the Pink Star), the Heart of Eternity (27.64ct), the Pumpkin (5.54 ct), the Moussaieff Red (5.11 ct), the Ocean Dream (5.51 ct) and the Allnatt. The literature that accompanied the exhibition clearly stated that Siba Corp. were the owners of the yellow diamond.

In their catalogue for the May 2024 sale, Sotheby’s did not identify the current owner of the diamond, stating only that it was “formerly in the collection of Major Alfred Ernest Allnatt.” The auction house showcased the yellow diamond in the promotional materials for the sale, clearly noting an auction estimate of 5.6 million to 6.5 million Swiss francs (or around $6.2 million to $7.2 million USD).

But less than a week before the planned sale, the Allnatt Diamond was suddenly withdrawn from the auction. In an article for National Jeweler, Lenore Fedow quoted a statement shared with the magazine by Sotheby’s: “It has been a privilege to present ‘The Allnatt’ to collectors and connoisseurs over the past few months. Following discussions with the consignor, they have elected to retain this jewel.” For now, the Allnatt will be staying with its current owners.