With Patek Philippe Extract from the Archives confirming production of the present watch with amagnetic movement 27-AM 400 in 1972 and its subsequent sale on 20 October 1972.
This watch is believed to be one of only two examples of a reference 570 fitted with an anti-magnetic movement 27-AM 400 known to date, a highly rare and unusual combination. Its exclusivity is further enhanced by the very well-preserved overall condition, underlined by the full and sharp case proportions and the crisp hallmarks. The unrestored dial displays a great shine, beautifully crowning the overall appearance of this elegant timepiece.
The large Calatrava model reference 570 was introduced to the market in 1938, featuring either subsidiary or sweep centre seconds. The present watch is from the first series made with subsidiary seconds but with the extremely unusual particularity of a 27-AM 400 anti-magnetic movement, normally reserved for Patek Philippe's "Amagnetic" watches such as references 2570/1 and 3460. The amagnetic calibre 27-AM 400 was launched in 1960 and is an improved version of the 1958 calibre 12'''400, fitted now with a Gyromax balance and free sprung self-compensation Breguet overcoil hairspring.
"Amagnetic" watches were designed for use in areas of high electro-magnetic fields such as in laboratories or electro-engineering. It can therefore be assumed that the original owner of this watch ordered it purposely with an amagnetic movement, as confirmed by the Extract from the Archives.