AUDEMARS PIGUET, REF. 5548BA, A FINE GOLD AUTOMATIC PERPETUAL CALENDAR WRISTWATCH

When it was launched in 1978, the Audemars Piguet's reference 5548 was the thinnest perpetual calendar wristwatch in the market. Developed by a team of engineers at AP as a secret side project, the movement was built using the reliable Jaeger-LeCoultre Cal. 920 movement as its base. The launch of an automatic perpetual calendar during the height of the Quartz Revolution was a daring move by the brand considering most traditional Swiss watch manufacturers were facing an existential threat from more economical (and reliable) Japanese quartz watches.

The present example No. 170, is among the earliest examples made. The ref. 5548 carries the 'Swiss' marking on the dial, as compared to the 'Swiss Made' seen on the later references. This reference was eventually be succeeded by the Ref. 25657.

Designed by Jaqueline Dimier, who also designed the first mid-size Royal Oak Ref. 4100 a year before in 1977, the Ref. 5548 was slim and svelte at 36 mm wide and less than 8 mm thick. It featured a circular brushed finish on the central caseback ringed by a grained-finish section. The case had a double stepped bezel and short lugs that help the watch sit comfortably on the wrist. It is believed that about 2,183 pieces were made of this reference, the majority of which were in yellow gold.