As a result, by 1951, when the rules governing the ‘chronometer’ designation imposed mandatory certification by an official rating centre (such as those in Neuchâtel, Geneva or Bienne), Rolex watches accounted for the majority of all the chronometers that had been officially certified since 1927.

After conquering precision, Hans Wilsdorf turned his attention to creating a perfectly hermetic environment for the movement. “To my technical assistants, my constant refrain from the earliest days was: ‘We must succeed in making a watch case so tight that our movements will be permanently guaranteed against damage caused by dust, perspiration, water, heat and cold. Only then will the perfect accuracy of the Rolex watch be secured’,” he explained.