A sunray ground under a set marker ring is a moving surface holding still objects. Reference 278285RBR is the 31mm Datejust in solid Everose gold with a bezel set with diamonds, and this configuration carries a slate dial set with diamonds and applied Roman numerals, on the President bracelet. Slate is one of the few grounds Rolex finishes with radial brushing rather than flat lacquer, so the dial brightens and darkens as the wrist rotates while the stones and the numerals stay exactly as bright as they were, which means the relationship between marker and background is never the same twice.
That instability is the whole interest of the configuration, and it is a property of the finish rather than the color. Sunray brushing is worked outward from the center in fine radial lines, and each point on the dial catches light at a slightly different angle from its neighbors, so a rotation of a few degrees changes which part of the surface is bright. Against a warm case that shifting grey picks up more Everose at some angles than at others, which keeps a neutral ground from settling into any fixed relationship with the metal around it. The Roman numerals are applied Everose and faceted, drawn for this case size rather than scaled from a larger one, and a full sequence occupies a considerable share of a 31mm dial before anything is set into it. The case is solid Everose rather than a two-metal combination, uniform from the lugs through the bracelet and considerably denser than steel, so the watch carries noticeably more mass than its size suggests. Everose is Rolex's own rose gold, cast in the brand's foundry and introduced in 2005, with a small proportion of platinum that stops the color drifting toward yellow across decades. 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. The bracelet is the President, semi-circular three-piece links with a concealed clasp folded away so completely that the bracelet appears continuous from every angle, tapering from the lugs toward the clasp so the mass sits forward on the wrist. The date at three displaces the numeral that would otherwise sit there. The hands are polished Everose and drawn short of the numerals so they cross the dial without appearing to touch them.
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. Rolex matches the date disc to the dial rather than leaving a paler window in a darker surface. The Cyclops lens above it has been part of the model 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 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 rotor winds in both directions rather than only one. The crown screws down against the case. Correction takes seconds and requires no tool.
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. Slate has appeared across several generations of the model without ever being the volume seller, and it is one of the few grounds Rolex offers with a sunray finish rather than a flat lacquer, which is why it behaves differently from every other neutral in the range. Roman numerals have never been the volume choice either. Solid gold references are built in far smaller numbers than the steel and two-metal ones. The President bracelet was designed in 1956 for the Day-Date and appears here as a borrowing. Within the generation, 278285RBR is the solid Everose reference with a diamond-set bezel. Sunray finishing is also considerably harder to keep even across a small dial than across a large one, since the radial lines converge more tightly toward the center. Slate is one of two grounds at this reference the catalogue lists both plain and set, and the set version here takes the large Roman six with eleven stones, an arrangement aubergine and chocolate also use.
The collector this suits wants a dial that does something rather than one that is something. Every flat lacquer on the reference presents the same face in every light, and this one does not, which makes it the configuration that rewards being worn over being looked at once. It is also the only dial here combining a moving ground, a full numeral sequence and set markers, so there are three separate things happening on a 31mm surface, and whether that reads as rich or as busy is the honest question a buyer should answer in person. Photographs are close to useless for deciding it, since a still image fixes the one thing about the dial that will not hold still. It is the configuration here that rewards being worn rather than examined once. Seven grounds are built at this reference and six of them carry stones on the dial, with only the President bracelet offered, so the ground and the marker arrangement settle the whole configuration.
