IWC Ingenieur SL Automatic Ref 3506 Grey "Graph Paper Dial" 1951 the same time most watch

the same time most watch companies switched from radium to tritium luminescent material

pie-pan-style dial reveals a subtle hint of light blue

reference 62510H

Vintage Datejust watches offer an incredible variety of dial configurations

The 36mm steel case is in superb condition

IWC Ingenieur SL Automatic Ref 3506 Grey "Graph Paper Dial" 1951 the same time most watchIn the mid 1970s, IWC decided to redesign the Ingenieur to give it a more "fashion forward" look. With this new model, IWC aimed to emulate the success of one of its rivals. A few years earlier, Audemars Piguet had struck gold with the luxury steel sports watch, the "Royal Oak," designed by Grald Genta. In response, IWC brought Genta on board (who also designed the steel Patek Philippe Nautilus) to redesign the Ingenieur, along with two other models: