To begin with, the Rolex Date-Just is the older design. It was first launched by the Swiss watchmaker in 1945. As such, some people think of it as a timeless design classic that has stood the test of changes in fashion and buying trends. However, the Day-Date isn’t that much younger. It was first presented in 1956 so there isn’t that much to separate them. Of course, watchmaking designs altered between the end of the Second World War and the mid-50s but both watches adhere to a common design aesthetic that sets them apart from Rolexes of the 1960s and 70s, for example, despite their visual differences.
In terms of calibre, vintage models of both the Date-Just and the Day-Date feature Rolex’s 3135 movement, a calibre that is often considered to have been at the very top of the industry for decades. That said, Rolex introduced the 3235 calibre movement in 2015. Since then, Date-Just models have been made with this new system and Day-Dates have retained the older, 3135 movement. This means that newer Date-Just models come with Rolex’s latest Chronergy escapement. This offers up to 15 per cent greater efficiency than the 3135 movement.
At about the same time, Date-Just models were updated with newer, KIF-style shock absorbers. Another technical distinction between Date-Justs and Day-Dates is that the latter allows for unrestricted rapid time and date setting while the former does not. In fairness, this is a detail that is hardly going to bother most owners.
