Rare Napoleonic Jewels Ignite Sotheby's Geneva Auction, Shattering Estimates

At Sotheby’s Geneva this past week, a long-lost treasure of Napoleonic history inspired one of the most electrifying jewelry auctions of the year. A diamond-encrusted hat ornament once owned by Emperor Napoleon Bonaparte — and believed to have been lost as he fled the Battle of Waterloo in 1815 — achieved a remarkable 3.5 million Swiss francs ($4.4 million).

Fueled by nearly 10 minutes of intense bidding among collectors on the phone, online and in the room, the jewel soared to more than 30 times its pre-sale low estimate. The result underscored not only the rarity of imperial French jewels, but also the unmatched power of provenance in today’s global jewelry market.

The circular ornament, crafted circa 1810, centers on a 13.04-carat oval diamond framed by nearly 100 old mine–cut diamonds in two concentric rings. Originally designed as a “hat button,” it would have adorned Napoleon’s iconic bicorne hat for court appearances, military pageantry and other highly visible occasions. Its brilliance and scale made it ideal for the emperor’s taste: opulent, symbolic and intended to project an unshakable aura of command.

But the jewel’s mystique comes from the chaos of its disappearance. As Napoleon’s forces retreated from Waterloo, several of his carriages became bogged down on muddy roads near Genappe, a town in current-day Belgium. Inside were not just uniforms and silverware, but a trove of jewels Napoleon had brought to the battlefield, including gifts from his siblings and items he famously carried everywhere — even into war. Prussian troops intercepted at least two of these carriages, claiming their contents as battle trophies.

According to historical accounts outlined by Sotheby’s, Lieutenant von Pless of the Prussian army presented the hat ornament to King Friedrich Wilhelm III just three days after the battle, declaring that such a rare object belonged with the Prussian crown. The jewel remained in the hands of the Prussian royal family, the House of Hohenzollern, for more than two centuries. Over time, it was photographed, cataloged and studied, its original hat-fitting replaced with a brooch mechanism and pendant loop, but its imperial identity remained unmistakable.

Its first appearance on the open market was enough to set collectors alight. Six determined bidders drove the price far beyond expectations, with a distinguished international collector, according to Sotheby's, ultimately claiming the piece. The strong result is part of a wider surge of interest in objects tied to Napoleon, especially following recent museum thefts that have reignited public fascination with French imperial jewels.

That momentum was reinforced by the sale of another Napoleonic treasure at the same auction: a 132.66-carat green beryl said to have been worn on Napoleon’s coronation robe in 1804. The gem achieved more than 25 times its low estimate when a US museum secured the stone for just over $1 million.

Together, the two sales delivered a powerful message: When exceptional craftsmanship meets extraordinary provenance, the market responds decisively.

Credits: Jewelry images courtesy of Sotheby's. Napoleon portrait by Peace Palace Library, Public domain, via Wikimedia Commons.