The Rolex Datejust was introduced in 1945 at the end of World War II and was at the time the first-ever self-winding wristwatch with a date function. Taking its inspiration from the Rolex “bubblebacks” or “Ovettone” from the 1930s and early 1940s, the case of the Datejust is aesthetically similar due to its bulging caseback developed for the self-winding rotor. The very first Datejust reference launched was the ref. 4467 and was only produced in yellow gold.