Swiss Haute Horlogerie manufacturer Audemars Piguet is pleased to announce the acquisition of one of its most historically important timepieces, the S. Smith & Son Astronomical Watch, known as the “Grosse Pièce”. Commissioned in 1914 and completed in 1921, this ultra-complicated pocket watch remained hidden from public view until the 1990s. Its welcome return to Le Brassus in the brand’s 150^th anniversary year reflects an enduring commitment to preserving watchmaking heritage and celebrating the art of horology.

The pocket watch was auctioned at Sotheby’s Important Watches sale in New York on 8 December 2025, as part of the landmark Olmsted Complications Collection.

Crafted in 18-carat yellow gold, the “Grosse Pièce” is the most comprehensive astronomical timepiece ever created by Audemars Piguet and among the earliest to feature a sky chart. It depicts the night sky over London with 315 stars, alongside sidereal time, a perpetual calendar, moon phases and the equation of time. The only ultra-complicated Audemars Piguet watch of the 20^th century, it also includes a minute repeater, grande and petite sonnerie, chronograph, and the brand’s only tourbillon in a pocket watch of that era.

With 19 complications, the “Grosse Pièce” ties with the legendary “Universelle” of 1899 as the most complicated Audemars Piguet pocket watch ever created. Like the “Universelle”, it is a living testament to the établissage system of the Vallée de Joux, which brought together specialised artisans to create some of the most complicated timepieces of the early 20^th century.

After its delivery to S. Smith & Son in 1921, the “Grosse Pièce” vanished from public view for decades, known only through archival notes and rare photographs. A document dated January 1915 reveals studies of sidereal time, zodiac signs, solstices and the state of the Northern Hemisphere sky – offering a glimpse into the pioneering spirit and craftsmanship that shaped the golden age of watchmaking.

For years, the watch remained within the prestigious Olmsted collection, admired only by a select few under the strictest discretion. Audemars Piguet’s acquisition of this revered timepiece at auction underscores the brand’s commitment to safeguarding horological heritage and showcasing exceptional savoir-faire. The “Grosse Pièce” will embark on a multi-year world tour, appearing at select AP Houses and special events before being exhibited at the Musée Atelier Audemars Piguet in Le Brassus.

DESCRIPTION
‘Grosse Pièce’ No.16869
An extraordinary, historically important yellow gold double dialled and double open-faced, minute repeating astronomical watch with one minute tourbillon, a celestial chart for the night time sky of London, day/night grande and petite sonnerie, chronograph, register for 60-minutes and 12-hours, perpetual calendar, moon-phases, equation of time, power reserve, and 24 hour sidereal time, Made for S. Smith & Son, Ltd., Started in 1914, shown at the Geneva Watch Exhibition in 1920 and delivered in 1921.

Movement: No. 16869, with 26’’’ “English” style, three-quarter plate, “Swiss” lever escapement, one-minute tourbillon with three-arm polished steel cage.

DIAL 1
Front: white enamel mean time dial, Roman numerals, four subsidiary dials indicating perpetual calendar calibrated for leap cycle, date combined with day of week, register for elapsed 60 minutes and 12 hours, ages and phases of the moon combined with up/down indication, the outer ring calibrated for equation of time.

DIAL 2
Back; Sidereal time, the dial silvered and gold over engine-turning, calibrated for 24 hours, in Arabic numerals enclosing an aperture revealing the celestial chart and its progress over London (51.5072° N, 0.1276° W) at any time of the day or night, showing 315 stars and various labelled constellations, all labelled in gold against a blue enamel ground, the chart further labelled on two silvered plaques Western Horizon and Eastern Horizon. Olivette hand setting for each dial.

CASE
85 mm 18k yellow gold case, with moulded bezels. The case band set with slides for choice of silent/striking and another for quarters/hours. Five-bar hinged case. Thief-proof swivel bow stamped with English hallmarks. The sky chart with the following named constellations: Perseus, Andromeda, Cassiopeia, Cepheus, Cygnus, Pegasus, Draco, Lyra, Serpens, Taurus, Scorpion, Corona Borealis, Hercules, the Great Bear, Virgo, Hydra, Cancer, Gemini, and Orion.

Signed: dial signed S. Smith & Son, Trafalgar Square, bezel interior stamped FT for Frederick Thoms, and London hallmarks.