Online bidding already exceeded the presale estimate for a diamond-set brooch once owned by Napoleon Bonaparte, the star lot of Sotheby’s Royal & Noble Jewels sale slated for 12 November in Geneva, Deutsche Welle reported.

Sotheby’s had predicted a hammer price of €120,000–€180,000. The auction house valued the piece at €130,000–€220,000, but the online component already moved past that range.

Discovered by Prussian troops on the Waterloo battlefield and presented to King Frederick William III on 21 June 1815, the jewel will go under the hammer for the first time. Circular and about 45 millimeters across, it was fashioned for Napoleon around 1810, probably to decorate his bicorne hat on formal occasions, according to Sotheby’s. The center holds a 13.04-carat oval diamond surrounded by nearly 100 old mine-cut diamonds in two concentric rows, and a suspension hook allows it to be worn as a pendant.

Legend says Napoleon abandoned the brooch along with medals, weapons, and a jewelry box while fleeing British and Prussian forces after the battle on 18 June 1815. Historians argue that the object marked the end of Napoleon I’s imperial ambitions and the rise of Prussia as a European power. It remained with the House of Hohenzollern for generations before moving to a private collection.

“It is a huge privilege to be able to bring to auction such wondrous pieces of jewellery, boasting prestigious provenance, year after year in Geneva,” said Andrés White Correal, head of noble jewels at Sotheby’s. He noted that the brooch carried great meaning for the Prussians, who had almost been erased by Napoleon before their victory at Waterloo.

Other stones expected to influence Geneva’s annual Luxury Goods Week totals include the 9.51-carat Mellon Blue diamond, valued at US$20 million–30 million. “The gem could shatter the world record for the price per carat of blue diamonds sold at auction,” said Tobias Kormind, managing director of 77 Diamonds, according to 24 Chasa. The Glowing Rose, a 10.08-carat vivid pink diamond estimated at about US$20 million, is also on offer. Sotheby’s will present a light-pink diamond ring of more than 13 carats once given to Neslishah Sultan with an estimate of CHF 240,000–400,000, and a natural pearl and diamond hair ornament from Cunégonde of Saxony’s collection, estimated at CHF 340,000–500,000.

Collectors will also see timepieces: on 9 November the house will auction a Rolex Oyster worn by endurance swimmer Mercedes Gleitze, the first British woman to cross the English Channel, expected to fetch more than €1.1 million.

“Provenance is not a mere detail; it is often what separates a beautiful piece from an object of absolute desire,” analysts said.

Written with the help of a news-analysis system.