The Audemars Piguet Quantième Perpetuel 25657OR is a rare 36mm pink‑gold perpetual calendar wristwatch from 1990, powered by the ultra‑thin automatic caliber 2120/2800 based on the Jaeger‑LeCoultre 920. Produced from 1982 to 1993 in only 1,821 pieces (fewer than 400 in pink gold), it is highly sought after for its technical sophistication, historical importance during the quartz crisis, and elegant, timeless design, and is considered a cornerstone piece for serious collectors.