Blancpain Fifty Fathoms diving watch specially engraved “AM” - The Blancpain watch company, along with Rolex, was one of the great pioneers of the underwater watch. The Fifty Fathoms model was designed in collaboration with undersea explorer Jacques Cousteau. Initially produced in 1953, it became the preferred watch for professional and military divers throughout the 1950s and early 1960s. This specially prepared “AM” – fpr “anti-magnetic”or “amagnetic” – model was designed for use by underwater EOD (explosive ordnance disposal) divers. Since many underwater explosive devices contain magnetic fuses, most of the ferrous components of this timepiece were replaced by copper-beryllium parts to minimize the watch’s magnetic signature. The watch case is made entirely of amagnetic mu-metal.