Every diamond on the outside of this watch is evenly spaced and every diamond on the inside is gathered into one place. 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 it with an olive green dial carrying a full Roman sequence in which the large VI is the only numeral set with stones, on the Oyster bracelet. That single loaded numeral is the whole difference between this dial and the marker version of it. The bezel runs its stones at a constant interval all the way round, and the dial answers with one bright point low on its face and plain gold numerals everywhere else. Very little else Rolex builds at this size sets up that kind of imbalance on purpose.
The setting is what separates this dial from every other gem-set option on the reference. Rolex does not scatter stones across the olive ground here or stand them at the hour positions; it opens the body of the large VI and sets the stones inside the numeral itself, so the gems read as a treatment applied to a marker rather than as markers in their own right. The numeral stays a numeral. That keeps the dial legible in the ordinary way, since a Roman sequence tells the eye where it is without the eye having to count, and it puts the brightest area of the dial at six rather than at twelve where decoration is usually placed. Olive green is applied as an opaque lacquer built up in thin coats so the tone holds even across the curve of the dial, and it is the darker of the greens Rolex offers on this case, closer to a field green than to the bright shades used on larger sport models. Steel and yellow gold divide the watch cleanly. Steel takes the case body and the outer bracelet links, and gold takes the bezel, the crown, the bracelet center rows, the numerals and the hands, all of it solid rather than plated or capped. The Oyster bracelet is three flat links, brushed across the top with polished flanks, closing on a concealed clasp folded away inside the links. The date sits at three beneath the Cyclops on a matched disc.
The Datejust does one thing beyond telling the time and it does it without asking anything of the wearer. The date changes instantaneously at midnight instead of drifting across the surrounding hour, which is the feature the model introduced in 1945 and the one it is named for. The disc is matched to the olive ground rather than left pale, so the window does not cut a bright rectangle into a dark dial, and the numeral inside it is drawn to sit level with the Roman sequence around it. The Cyclops lens above the window has been fitted to the Datejust since 1953 and enlarges the numeral roughly two and a half times, which on a 31mm dial is the difference between a date that is read and a date that is guessed at. Correction runs through the winding crown at its own position, without moving the hands and without a separate tool. The movement is self-winding with a power reserve of approximately 55 hours, and that figure belongs to a movement built for a case this size rather than carried over from a wider one, since a smaller barrel stores less energy and a smaller rotor collects less of it from the same arm. The crown screws down against the case. Everything the watch needs from its owner is regular wear.
The Datejust arrived in 1945 as the first self-winding wristwatch to display the date in a window, and it has been made continuously since, which makes it the longest-running model in the range. The 31mm case sits between the 28mm Lady-Datejust and the 36mm original and exists for buyers who find one too small on the wrist and the other too broad. The 278000 generation replaced the 178000 series in 2018 with a reworked case and bracelet. Rolex registered the name for its steel and gold construction in 1933, on the argument that steel does the structural work and gold does the visual work, and that division still describes exactly how this watch is built. Colored lacquer dials are recent on the model by comparison. Rolex ran them for decades in small numbers before the current generation made them a standing part of the catalogue, and green in particular has moved from an occasional release to a fixed option across several references. Within the generation, 278343RBR is the steel and yellow gold reference with the diamond-set domed bezel, and it offers the olive ground in two forms: this one, with the Roman sequence and the set VI, and a version in which the numerals are removed and the stones stand at the hour positions instead. Those two are different watches sharing a ground, and buyers who have handled both rarely find them interchangeable.
The buyer for this wants a gem-set watch that still reads as a watch. A Roman sequence gives the dial a structure that a ring of stones cannot, and setting only the VI keeps the ornament to one place instead of distributing it, which is a quieter decision than the bezel would suggest from across a room. That combination is uncommon. Most decorated dials at this size commit fully in one direction or the other, and this one holds both positions at once. The Oyster bracelet reinforces it, since three broad links are the plainer of the two options here and keep the watch built for regular wear rather than for occasions. Olive green does the same work, reading as restraint at conversational distance and only showing itself as a choice up close. Buyers who came to the reference for the bezel and then found the fully gem-set dials too uniform tend to arrive here, and buyers who wanted a green Datejust with something more than plain markers arrive from the other direction. The reference holds both without asking either to compromise.
