AUDEMARS PIGUET Quantieme Perpetual 5557AC two tone – 1980s

The 5557CA is part of AP’s pioneering ultra-thin automatic perpetual calendar family from the early 1980s, powered by the cal. 2120/2800 derived from JLC’s famed 920. Its 18k white & yellow gold octagonal case with a round stepped bezel and the integrated woven bracelet give it a distinctive “Genta-era” look. Diameter is catalogued around 35.5 mm. Many dealers nickname it “Royal Oak Perpetual Calendar,” though AP catalogues it as Quantième Perpétuel Ref. 5557CA – a design that directly preceded and inspired the later Royal Oak QP.