The Rolex Replica Datejust was initially designed in 1948 by Henry Graves, and he had no idea how to make them mechanical. Today, they are still the only automatic chronograph watch made by Rolex. The first version of the clock was created in 1948, but it didn’t display a date. Hence, when Graves bought his first cheap clock, he made it himself from scratch, incorporating an atomic reference clock that included a lot of calculations for keeping accurate time.