The inaugural Royal Oak model, reference 5402, made its debut in 1972 at the Basel Fair following two years of meticulous development. Apparently designed in one night by Gérald Genta, this extraordinary watch elevated steel to a new status. It pioneered the concept of "casual chic," marking a pivotal moment in the history of Audemars Piguet and luxury watchmaking.

Designed in 1977 by Jacqueline Dimier, the Royal Oak reference 4100ST was the third Royal Oak produced in history, and the first ‘mid-size’ model, offering a smaller alternative to the reference 5402 which, with its 39 mm diameter, was considered a large watch for the time. It was in production for eight years, but were continuously sold until 2002. The 4100 is the largest series of all the so-called ‘mid-size’ Royal Oaks, with more than 8,400 units sold. In terms of design, purists will appreciate the ‘small font’ typography, as well as the proportions, which are an elegant mix between the first two references in history, the 5402 and the 8638. The 4100 also features a case back that separates from the case, a first at the time for the Royal Oak, which was still only designed in two parts.

This particular watch has the original blue dial, which has beautifully tropicalised, acquiring a superb tint over time. All the parts are original, including the crown, which is not screwed down on the 4100 and was almost always replaced during servicing at Audemars Piguet. The case and bracelet are made of steel and have been kept in great condition. The calibre 2123 is the original calibre.