This reference and 278278 build the same twelve dials in the same arrangements, and the bezel is the only thing separating them. On ten of those dials the stones on the rim join stones on the face. On the other two they are the only stones on the watch. Reference 278288RBR is the 31mm Datejust in yellow gold, carrying a bezel set with diamonds, and this configuration pairs a plain white dial with a full set of Roman numerals, fitted to a President bracelet. It is one of the two, and it is the version where the difference between the two references is the entire difference between the two watches.
The case is solid yellow gold at thirty-one millimeters and the bezel is set with diamonds rather than fluted, which changes what the rim does with light. A fluted bezel breaks light into a repeating run of highlights and shadows following the shape of the cut; a set bezel returns it in points that flare and go dark as the wrist moves, with no pattern to them at all. The dial is a flat white that does not change at any angle, and Roman numerals in gold stand at the hours, applied at a uniform size with nothing enlarged and no stone anywhere on the face. That combination puts every moving element on the outside of the crystal and every fixed one inside it. The President bracelet is semi-circular three-piece links in the same gold, rounded across their width, and it is the only bracelet this reference offers. The watch has one still surface on it and it is the one carrying the information, while everything around it is in motion. On the set dials that hierarchy does not exist, because the stones inside the crystal move in the same way the stones on the rim do. Here the two are kept apart, and the dial is left as the only part of the watch that looks the same in every photograph taken of it. Every stone on this watch sits outside the crystal and none of them sits inside it, which is the reverse of how the other ten configurations on the reference are arranged.
Hours, minutes, running seconds and a date that advances in a single step at midnight rather than easing over into the following day. The self-winding movement in the 31mm case holds roughly fifty-five hours of running time, matching the 28mm references rather than the 36mm ones, which run a movement of their own. Roman numerals tell the eye which hour each position is rather than only where the hours are, so the dial can be read without reference to the hands, and on a flat white ground with gold characters that reading is as fast as this reference gets. The bezel does not help and does not have to. The date window at three is the only break in the numeral sequence, framed in gold and absorbed into the same system as the markers. At this diameter the numerals are close to the smallest Rolex prints them, and a white ground is what keeps the set from crowding, since it gives each character the maximum separation available. Choosing them under a set bezel is choosing to keep the dial doing one job while the rim does another. That division is why the configuration survives on a reference where ten of the twelve dials are set: someone specifying this watch wanted the stones and wanted to keep the face clear, and the catalogue treats those as compatible rather than contradictory.
White with Roman numerals is built on all seventeen references at this size, which no other ground manages, and it comes one way here; the applied-marker version of the same ground exists at 36mm and 41mm but not at 31mm. That makes this dial the constant across the whole size, from the plain steel reference through the two-metal cases to the five solid gold ones. What varies is everything around it. Within this reference white is one of two unset dials, the other being champagne with applied markers, and the remaining ten configurations carry stones on the face. Against its twin, the identical dial on 278278 sits under a fluted bezel, and a buyer comparing the two references on this ground is choosing between a rim that is worked metal and a rim that is set with stones, with nothing else in the comparison. That is a cleaner decision than the same comparison on any set dial, where the two rings of stones interact and the bezel changes how the dial itself reads. On this ground the dial is unaffected by what happens at the rim, so the two references produce two clearly separable watches rather than two versions of one, and that is unusual enough at this size to be the main reason for choosing between them.
This is a plain dial under a set bezel, and it is a deliberate combination rather than a compromise. The watch carries stones and does not look like a diamond watch from the front, because the only place they appear is the rim and the rim is read as part of the case. Anyone who wants the setting to be the whole statement should take one of the ten set dials here, where the stones appear twice. Anyone who wants no stones at all should take 278278, which builds this same dial under flutes. Between those two positions this configuration is the narrow middle: formal on the face, decorated at the edge, and legible in a way none of the set dials on this reference are. It is also the version that ages least conspicuously, since the dial is the part of a watch that dates it and this one has been built essentially unchanged for as long as the model has existed.
