The Rolex caliber 3255 is an in-house automatic movement found in the Rolex Day-Date 40. This caliber was originally announced at Baselworld 2015.
Rolex claims the new caliber 3255 is two times more precise than an officially certified chronometer. The technology within is protected by 14 patents acquired by “The Crown”. One of the patents includes the Paramagnetic Oscillator with new balance staff that offers enhanced resistance to magnetism.
“Calibre 3255’s criteria for precision in everyday wear are twice as exacting as those for an officially certified chronometer. It incorporates the new Chronergy escapement patented by Rolex, which combines high energy efficiency with great dependability. Made of nickel‑phosphorus, it is also insensitive to magnetic interference. The oscillator, the true heart of the watch, has an optimized blue Parachrom hairspring, which is also up to 10 times more precise than a traditional hairspring in case of shocks. Thanks to a new barrel architecture and the escapement’s superior efficiency, the power reserve of calibre 3255 extends to three days. This means the watch will easily continue to run from Friday evening into Monday afternoon even if not worn or wound.” -Rolex