Patek Calatrava Porcelain Dial Clous de Paris 18k Yellow Gold Case with Extract from the Archives ref. 3919This fine Calatrava ref. 3919 was introduced in 1985 as a response to the Quartz Crisis, with then president Philippe Stern aiming to highlight the value of mechanical watchmaking. The 33. 5 mm 18k yellow gold case reflects the minimalist elegance of the original Calatrava line, but features the distinctive Clous de Paris (hobnail) bezel. The bezel consists of two concentric circles of small pyramid shapes, now considered a timeless classic.