Three surfaces on this watch return light and one holds still. Reference 278243 is the 31mm Datejust in a combination of stainless steel and yellow gold with a domed yellow gold bezel, and this configuration pairs a silver dial set with diamonds and applied Roman numerals with the Jubilee bracelet. The reflective ground moves with the light, the diamonds move with it, and the five rows of alternating steel and gold across the wrist move with it too, so the only fixed element anywhere on the object is the numeral sequence. On the Oyster version the bracelet at least stays flat. Here nothing does.
The Jubilee's five links across the width put yellow gold center rows between steel outer links, and because yellow gold sits nowhere near steel in color the alternation reads as a clear boundary between two materials rather than as a change in finish, which means the bracelet is contributing contrast rather than merely texture. The gold is solid rather than plated or capped, and Rolex matches the polish on the center rows to the polish on the bezel so the metal reads as one material distributed rather than as separate applications of it. The bracelet also carries roughly twice the component count of the Oyster across the same width, which is why it articulates more finely and follows a wrist more closely. Silver is a reflective ground rather than a colored one, taking on whatever surrounds it, so inside this case it picks up a gold cast it does not possess and runs warmer under a low lamp than in daylight. Rolex draws the Roman numerals for each case size rather than scaling a single set across the range, and a full sequence occupies a considerable share of a 31mm dial before anything is set into it. The domed bezel above is smooth and unbroken, the quietest shape the model is offered with, and on a watch this active it is the only element not participating. The date at three displaces the numeral that would otherwise sit there. The hands are polished yellow gold and drawn short of the numerals so they cross the dial without appearing to touch them, and Rolex proportions the aperture frame for each case size as well, since a window drawn for a larger dial crowds a smaller one. The lugs are finished so the bracelet meets the case without a visible gap at any angle of articulation, which is a tolerance rather than a feature and among the clearest differences between this generation and the one before it. Rolex also matches the height of the marker settings to the height of the date frame, so the dial reads as one plane with elements standing off it rather than as several plates at different levels.
The date is the only indication the watch carries beyond the time, and a single aperture is what allows a full Roman sequence to fit at all. The Cyclops lens above it has been part of the Datejust since 1953 and magnifies the date roughly two and a half times, which makes a small window readable without enlarging it and unbalancing the dial. The date changes instantaneously at midnight rather than creeping through the surrounding hour, the feature the model introduced in 1945 and the reason it carries the name it does. Correction runs through the winding crown without advancing the hands, and nothing the watch asks for requires a tool. The movement is self-winding with a power reserve of approximately 55 hours, engineered into a movement built to fit a 31mm case rather than carried down from a larger one, since a smaller barrel stores less energy and a proportionally smaller rotor supplies less of it. The rotor winds in both directions rather than only one, which lets a movement this size keep itself running on the wrist movement of an ordinary day. The crown screws down against the case, and the Jubilee closes with a concealed clasp folded away inside the links. Correction takes seconds and requires no tool.
The Datejust arrived in 1945 as the first self-winding wristwatch to show the date in a window, and the Jubilee was introduced the same year for that watch, which makes it native to the model rather than an option added later. The 31mm case sits between the 28mm Lady-Datejust and the 36mm original, and the 278000 generation replaced the 178000 series in 2018 with a revised case and bracelet. Rolex registered the name for its steel and gold construction in 1933. Silver has been in the dial range across every generation and is one of the few grounds that has never left it. Within the generation, 278243 is the steel and yellow gold reference with a domed bezel. Gem-set dials have also been part of the model for most of its history and remain a minority of what Rolex builds in any given year, which is why they turn up on the open market in smaller numbers than the catalogue would suggest. Silver is one of three grounds here built in two set arrangements, alongside dark grey and olive green, and this is the version that carries the enlarged six at six rather than stones standing in place of the markers alone.
This suits a buyer who wants the watch to be alive in every light and is not troubled by having to look twice to read it. The numerals make that possible, since without them a reflective dial carrying reflective stones on a reflective bracelet would give the eye nowhere to land at all. That is the whole reason the Roman version of this ground exists alongside the marker version. It is also the more comfortable of the two bracelet options at this size, following a small wrist more closely, so the busier choice is again the better-wearing one. Buyers weighing it against the marker version of the same ground are choosing whether the dial should have an anchor or not. Those three grounds take four of the twenty-two rows each, and only champagne and white are offered unset at all, which leaves eighteen of the rows here carrying stones on the dial.
