The history of this Audemars Piguet Royal Oak
Unveiled in 1977, this 18-carat yellow gold Audemars Piguet Royal Oak 4100BA is the third model in the collection, following the 5402 from 1972 and the 8638 – the first ladies’ model – hence its name, Royal Oak III, in the brand’s archives. Designed by Jacqueline Dimier, it was created in response to a specific demand. For some customers in Italy, the United States and Asia, the 39 mm case of the 5402 was too imposing. The Royal Oak 4100 reduced the diameter to 35 mm and became the first Royal Oak to feature a central seconds hand, thanks to a more compact calibre developed specifically for it. Audemars Piguet presented it in 1978 at the Basel Fair as a Royal Oak designed for slender wrists. In yellow gold, 2,130 pieces were sold between 1977 and 1988, featuring several dial variations.
Case, movement and bracelet of this Royal Oak
The 35 mm case echoes the design created by Gérald Genta for the first Royal Oak. The satin-finished octagonal bezel, edged with a polished chamfer, is held in place by eight visible hexagonal screws, whilst the screw-down caseback, engraved with ‘Royal Oak’, is secured by eight screws. The crown bears the AP monogram. Beneath the sapphire crystal, the grey Petite Tapisserie guilloché dial features an applied AP logo, gold baton hour-markers and baton hands coated with luminescent material, with a date window at 3 o’clock. The self-winding Calibre 2123, based on a LeCoultre movement, beats at 28,800 vibrations per hour and contains 33 jewels. With a diameter of 26 mm, it marks the beginning of the Maison’s line of 26 mm automatic calibres. The integrated 18-carat yellow gold bracelet, with satin-finished links and polished edges, fastens with an AP-signed folding clasp.
Why this Audemars Piguet watch
Produced until 1985, the Royal Oak 4100 is now only available on the second-hand market. This particular example was serviced by Audemars Piguet in 2026, with its movement replaced by a calibre 2123. For a vintage Royal Oak over 45 years old, this ensures the movement has been tested by the manufacturer, without the uncertainties associated with an older calibre of unknown provenance. Measuring 35 mm, the satin-finished case slips easily under a cuff, allowing the Petite Tapisserie dial to take centre stage. This is the proportion intended in 1977 – more understated than that of today’s Royal Oak models – for those seeking the collection’s original design in yellow gold, complete with a recent service by the Maison.
Contents and condition
It is supplied in its green Audemars Piguet octagonal case, with the brand’s service outer box, a Royal Oak Automatic booklet, the service invoice dated June 2026 and the quotation dated September 2025. This service included a movement replacement and a partial water resistance test. The watch has been worn and shows slight signs of wear on the satin-finished surfaces of the case and bracelet, with no obvious impact marks, which corresponds to very good condition. Originally designed to be water-resistant to 50 m, it is now over 45 years old and its original water resistance is no longer guaranteed. It should therefore be kept away from water.
Warranty and delivery
The Swiss Collector guarantees the authenticity of this watch, which is covered by a 24-month warranty. We accept returns within 10 days in accordance with our terms and conditions. As Switzerland’s leading second-hand retailer, backed by the largest network of shops, we offer online booking for a fitting and collection in-store, or fully secure international delivery.
* Very good condition – watch has been worn. Slight signs of external wear. Case and strap in excellent overall condition.
