Measuring 31mm across, the round case of this Datejust 31 is crafted in White Rolesor — Rolex's combination of Oystersteel and white gold — and features a monobloc middle case, a solid screw-down case back, and a screw-down Twinlock winding crown for waterproofness to 100 metres. The bezel is set with diamonds, while a scratch-resistant sapphire crystal with a Cyclops lens over the date window sits above the white dial marked with Roman numerals.
Power comes from the Calibre 2236, a perpetual mechanical self-winding movement manufactured by Rolex and rated to a precision of -2/+2 seconds per day after casing. It features a Syloxi silicon hairspring with patented geometry, high-performance Paraflex shock absorbers, bidirectional winding via a Perpetual rotor, and a power reserve of approximately 55 hours. Functions include centre hour, minute, and seconds hands, an instantaneous date with rapid setting, and stop-seconds for precise time setting.
The three-piece solid-link Oyster bracelet is rendered in Oystersteel and secured by a folding Oysterclasp fitted with an Easylink 5mm comfort extension link. Reference 278384RBR-0013 is COSC certified and carries the date complication as its sole additional function.
