Of everything built on this reference, this is the configuration that looks least like a diamond watch. Reference 278344RBR is the 31mm Datejust in a combination of stainless steel and white gold with a domed bezel set with diamonds, and this version pairs it with a dark grey dial and applied Roman numerals, on the Oyster bracelet. A sober neutral ground, the most formal marker set Rolex fits, a flat working bracelet and a case whose second metal is invisible. Everything about it reads as restrained, and the bezel is the only element that gives away what the watch actually costs to make.
Roman numerals occupy more of a dial than any other marker set Rolex offers, and Rolex draws them for each case size rather than scaling a single set across the range, so the ones fitted here are proportioned for a 31mm dial rather than inherited from a larger one. Applied in white gold and faceted, standing off the surface rather than printed onto it, they read against a mid-tone grey by a combination of their own brightness and the shadow they throw, which is a more balanced relationship than they achieve on either a pale or a black ground. The dial is an opaque lacquer laid down in several thin coats so it holds one value regardless of the angle it is seen from, and grey is the most neutral of the deep colors offered here, cooler than chocolate and considerably lighter than aubergine. The case is a combination of stainless steel and white gold, the least visible two-metal pairing Rolex makes, since white gold sits close enough to steel in color that most people never register the watch as two-tone at all, and the bezel is white gold set with diamonds, so the stones cover most of the only surface where the second metal would be identifiable. White gold is considerably denser than steel, which means that bezel is noticeably heavier than a steel one of identical dimensions, and the extra mass sits at the outer edge where weight registers most. The bracelet is the Oyster, three broad flat links brushed across the top with polished flanks, returning light in plain sheets. The date at three displaces the numeral that would otherwise sit there, on a disc matched to the dial with a polished white gold frame set flush with the lacquer. The bezel stones are seated individually into recesses cut in the gold rather than dropped into a preformed channel, and on a ring this small there is less circumference to absorb an error, so the tolerances run tighter than they would on a larger bezel of the same design.
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, since a second window would leave no room for twelve numerals on a dial this size. Rolex matches the date disc to the dial rather than leaving a white window in a darker surface, which decides whether the aperture belongs to the watch or interrupts it. The Cyclops lens above it has been part of the Datejust since 1953 and remains the most recognizable thing about the model at a distance, and against a mid-tone ground the magnified numeral has ample contrast. The date changes instantaneously at midnight rather than creeping through the surrounding hour, the feature the Datejust introduced in 1945 and the one it takes its name from. Correction runs through the winding crown without moving the hands, and nothing the watch asks for requires a tool. The movement is self-winding with a power reserve of approximately 55 hours, an engineering result on a movement built to fit a 31mm case rather than a figure carried down the range, since a smaller barrel has less room to store energy and a proportionally smaller rotor gathers less of it. The crown screws down against the case, and the Oyster closes with a concealed clasp folded away inside the links.
The Datejust arrived in 1945 as the first self-winding wristwatch to show the date in a window, and the 31mm case sits between the 28mm Lady-Datejust and the 36mm original, which makes it the size for buyers who find one too small and the other too large. The 278000 generation replaced the 178000 series in 2018 with a revised case and bracelet. Roman numerals have been offered across most of the model's history and have never been the volume choice. Dark grey has appeared across several generations without ever being the volume seller either, which is part of why the combination reads as chosen rather than defaulted to. Rolex casts its own gold in a foundry on its premises, which is unusual in the industry and is the reason it can hold an alloy to a consistent tone across decades of production. Within the generation, 278344RBR is the steel and white gold reference with a diamond-set domed bezel. Steel and white gold exists largely for buyers who want the construction of a two-tone watch without the appearance of one, which is a narrower proposition than the Everose and yellow references answer and a more deliberate one. Dark grey is offered here both plain and set.
The buyer for this wants a set watch that will not be read as one from the front. Every other gem-set or colored configuration on the reference declares itself immediately, and this one declares nothing until the light catches the bezel, which for a great many buyers is the entire specification rather than a compromise within it. It is also the most legible dial here after the bright black, since a mid-tone ground and applied numerals resolve instantly in any condition. On the Oyster it is built to be worn through an ordinary week rather than saved, which very few watches with a diamond bezel genuinely are. Dark grey takes eight of the reference's thirty-two rows, level with pink and more than any other ground, since it is built in two marker treatments unset and in two arrangements when set. That is the widest reach of any ground anywhere on the roster.
