Reference 278240-0007 houses the Datejust 31's round, 31 mm Oystersteel case within the classic Oyster architecture: a monobloc middle case paired with a screw-down case back and a screw-down Twinlock winding crown for waterproofness to 100 metres. A scratch-resistant sapphire crystal tops the case, complete with a Cyclops lens magnifying the date, while the domed bezel frames the pink dial beneath.
The pink dial features index hour markers and a Chromalight display, whose long-lasting blue luminescence ensures legibility in low light. Powering the watch is the Calibre 2236 — a perpetual, mechanical, self-winding movement from Manufacture Rolex — with a Syloxi silicon hairspring and Paraflex shock absorbers. It delivers a power reserve of approximately 55 hours and a precision of -2/+2 seconds per day after casing, earning Superlative Chronometer status through both COSC and Rolex certification.
The Oystersteel Oyster bracelet, constructed from three-piece solid links, fastens with a folding Oysterclasp that incorporates an Easylink 5 mm comfort extension link for on-the-fly size adjustment. The movement provides centre hour, minute, and seconds hands alongside an instantaneous date with rapid setting and a stop-seconds function for precise time setting.
