Audemars Piguet QP Skeleton 5558BA Mk1 1986

Audemars Piguet Pepetual Calendar (QP), Skeleton, 18K yellow gold
Serial: N 038 / B86369 / Mvt 274017
Circa: 1986
Reference: 5558BA

DIAL: Transparent mineral crystal with cream colored registers

CASE: 36mm, 18K yellow gold, sapphire crystal on the front & on the back

MOVEMENT: Caliber 2120/2800, skeletonized automatic perpetual calendar, 38 jewels

BRACELET: Leather strap with Audemars Piguet 18k yellow gold ardillon buckle

CONDITION REPORT: Worn, mint condition, the case is unpolished and all hallmarks and numbers are ultra crisp and developed a warm patina over time.

NOTES: A very early example of the skeleton perpetual calendar bearing the number 038.
The Audemars Piguet ref. 5558 (prior to the reference being changed to 25558 in 1987) is the skeletonized version of the brand’s famous ultra-thin perpetual calendar introduced in the late 1970s, during the Quartz Crisis. Using the legendary Calibre 2120/2800, it combined a full perpetual calendar with an exceptionally thin automatic movement.
What made the 5558 special was its hand-openworked construction: the movement bridges were carefully skeletonized and engraved, turning the mechanism itself into the dial. Produced in very small numbers, usually in yellow gold or platinum, the 5558 became one of AP’s most collectible vintage complications.
The watch helped preserve traditional Swiss high watchmaking at a time when mechanical watches were under serious pressure from quartz technology, and it paved the way for later Audemars Piguet perpetual calendar masterpieces.