This is the same set of stones asked to do two different jobs on one wrist. 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 pairs a dark grey dial set with diamond markers with the Jubilee bracelet. The bezel ring exists to frame the watch and reads as a continuous band of brightness against gold, and the dial ring exists to mark the hours and reads as twelve distinct points against dark lacquer. Identical material, opposite functions, and the grounds are what make each one work.
The Jubilee then adds a third repetition of its own. Its five links across the width alternate yellow gold center rows with steel outer links, and because yellow gold sits nowhere near steel in color that alternation reads as a clear boundary between two materials rather than as a change in finish, so the wrist carries its own pattern rather than acting as a plain backing. The bracelet 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, and the gold is solid rather than plated or capped. 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 bezel stones are seated individually into recesses cut in the gold and graded for size so the ring reads as even around its circumference. On the dial the markers stand slightly proud of an opaque lacquer laid down in several thin coats, and Rolex keeps the settings low and tight since a raised marker on a 31mm surface has little room before it crowds the hands. The date sits at three under the Cyclops lens on a matched disc, its frame polished gold and set level with the surface. Rolex matches the height of the marker settings to the height of the date frame as well, so the dial reads as one plane with elements standing off it rather than as several plates at different levels, and the hands are polished yellow gold drawn for this case size rather than scaled from a larger one. The aperture frame is proportioned the same way, since a window drawn for a larger dial crowds a smaller one.
Rolex matches the date disc to the dial rather than leaving a paler window in a darker surface, and a single aperture keeps the marker ring uninterrupted where a second would break a pattern depending on continuity. 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. Hand winding runs through the same crown with no separate position to learn. The crown screws down against the case, and the Jubilee 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, and correction takes seconds without requiring a 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. 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. Dark grey has appeared across several generations without ever being the volume seller, and gem-set markers have been offered on it for most of that time. 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, which is worth knowing on a watch carrying both. Grey has stayed in the range far longer than most of the grounds introduced alongside it, and the gem-set versions have followed it throughout rather than appearing and being withdrawn. Within this reference grey carries stones in every version the catalogue lists, and it is one of three grounds, with olive green and silver, offered in two marker arrangements rather than a single one.
The buyer for this wants everything decorated and still wants to be able to read the time. That combination is harder to find than it sounds, since most fully set configurations sacrifice legibility to get there, and a dark ground is what makes it possible here by giving the markers contrast the bezel cannot have. Among the four gem-set grey and silver configurations across this reference, this is the one that carries the most and gives up the least. It is also the more comfortable of the two bracelet options at this size, so the fullest specification is again the better-wearing one. Anyone shopping the four should expect the ground rather than the bracelet to make the decision, since that is what changes how the stones behave. Seven grounds are available here and six of them are set, so the choice is mostly between one treatment and another rather than between stones and none. Either bracelet is open on all of them.
