This watch carries diamonds on both sides of the crystal, and the two sets live very different lives. Reference 278343RBR is the 31mm Datejust in a combination of stainless steel and yellow gold with a domed bezel set with diamonds, and this configuration carries a silver dial set with diamonds and applied Roman numerals, on the Oyster bracelet. The bezel stones sit exposed at the outer edge of the case where they meet cuffs, doorframes and everything else a wrist encounters, and the dial stones sit sealed beneath sapphire where nothing reaches them. Same material, same setting technique, entirely different exposure.
That distinction matters more over decades than it does in a showroom. A bezel stone can be knocked, and a dial stone cannot, which is why gem-set dials outlast gem-set bezels on watches that get worn hard and why the two are valued and serviced differently. Rolex seats the bezel stones individually into recesses cut in the gold rather than dropping them 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. Because yellow gold is visible enough not to be overtaken by stones, the bezel reads as gold with diamonds in it rather than as diamonds alone, which is the more traditional presentation. On the dial the markers are set into a reflective silver ground, and silver returns whatever light reaches it exactly as the stones do, so the two change together and the applied Roman numerals are the only element on the surface holding a fixed value. Rolex draws those 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. Steel and yellow gold is the most visible two-metal pairing the brand makes, and here the steel forms the case and the outer bracelet links while the gold takes the bezel, the crown, the bracelet center rows and the numerals. The gold is solid rather than plated or capped. The bracelet is the Oyster, three broad flat links brushed across the top with polished flanks, tapering toward the clasp so the weight sits forward on the wrist. The date at three displaces the numeral that would otherwise sit there.
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 already carrying stones. The Cyclops lens above it has been part of the Datejust since 1953 and magnifies the date roughly two and a half times, and against a reflective ground the magnified numeral has as much contrast as the dial can give it. 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. Hand winding runs through the same crown with no separate position to learn. The crown screws down against the case, and the Oyster closes with a concealed clasp folded away inside the links. A movement of this size gathers less from the same wrist movement than a larger one, so the watch does better worn daily than kept aside between outings.
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. Rolex registered the name for its steel and gold construction in 1933, on the reasoning that steel supplies the structure and gold supplies the color. Silver has been in the dial range across every generation and is one of the few grounds that has never left it, and Roman numerals have never been the volume choice within that. Within the generation, 278343RBR is the steel and yellow gold reference with a diamond-set domed bezel. Gem-set bezels are also serviced differently from gem-set dials, since a bezel can be reworked without opening the case and a dial cannot. Silver is one of three grounds at this reference offered in two set arrangements, with dark grey and olive green taking the same pair, and it appears only with stones on the dial. Of the seven grounds here, five are set-only, champagne comes both ways, and white is never set.
The buyer for this wants the stones in both places and should understand that only one set is protected. That is not an argument against the bezel, which is built to be worn and repaired like any other part of the watch, but it is the practical difference between this reference and the plain-bezel version of the same dial, and it is worth knowing before rather than after. The numerals are the other consideration, since without them a dial this reflective would have nothing fixed on it at all. Between the four silver configurations across this reference and its plain-bezel sibling, this is the one that carries the most and still reads at a glance. Buyers weighing it against the plain-bezel version of the same dial are choosing how much of the decoration should be exposed. The same dial is offered on either bracelet, as every ground at this reference is, so the bracelet is a separate decision from the marker arrangement rather than a consequence of it.
