Introduction and Launch: The Rolex calibre 745, introduced in 1952, was an automatic movement used in Datejust models from 1952. Many of Rolex’s earliest watches, including those with this calibre, were not chronometer-certified. While the “Superlative Chronometer Officially Certified” text on modern Rolex dials signifies precision and prestige, some collectors appreciate the cleaner aesthetic of non-COSC dials with less text.