27. 27Y Audemars Piguet. A fine 10th Anniversary Limited Edition 18K gold automatic perpetual calendar wristwatch with moonphase Audemars Piguet. Belle montre bracelet en or jaune 18K (750) calendrier perpétuel et phase de lune mouvement automatique Model: Quantième Perpétuel Automatique Edition Spéciale, 50 pieces created exclusively for the German market, No.29/50 Reference: 25661BA Date: Purchased in December 1988 Movement: 38-jewel Cal.2120/2 automatic, adjusted to cold, isochronism and 5 positions, 21K gold rotor, No.294144 Dial: White, applied gilt baton hour markers, black outer minute divisions, subsidiary dials at 12, 3 and 9 for day, date and month, moon phase indication at 6, gilt pointed baton hands Case: Brushed and polished round, snap on exhibition back, stepped bezel, quick set buttons at 4, 8 and 10 Strap/Bracelet: Audemars Piguet black alligator leather Buckle/Clasp: Signed 18K gold buckle Signed: Case, dial & movement Size: 36mm Weight: 54,29g Accompaniments: Audemars Piguet watch winding box, outer card, Certificate of Authenticity and Exclusivity, Certificate of Origin and Guarantee, travel pouch with outer card, quickset tool, box key, Instructions manual Conceived in secret and launched in the midst of the quartz crisis, Audemars Piguet's 1978 release of the world's thinnest self winding perpetual calendar wristwatch was one of the greatest horological innovations of the late 1970s. Jacqueline Dimier, famed for her incredible contribution to the Royal Oak, was the design mastermind behind the original 5548 Perpetual Quantieme. The 5548 was her playground from which she went on to design a vast number of magnificent models and variations. Often mistaken for reference 25657 the reference 25661 offers a visually treat courtesy of a snap-on sapphire crystal display back, highlighting the incredibly craftsmanship of the ultra-thin movement. This reference can be found in late C and early D series. Introduced just 3 years after the ref. 25657 production of the ref. 25661 ran in parallel with most design features being shared across the references such as the sunken sub-dials.