Two grounds take the oversized six on Everose and on nothing else. Chocolate and slate are locked to this alloy in that treatment, exactly as silver and olive green are locked to yellow and pink to white gold; only aubergine and dark grey cross between families. An oversized six on a slate dial therefore identifies an Everose case without any other information being needed. Reference 278275 is the 31mm Datejust in Everose gold, carrying a fluted bezel, and this configuration pairs a slate dial set with an oversized six carrying eleven diamonds, fitted to a President bracelet. Slate is one of two grounds at this reference offered both plain and set, rose being the other, and four further grounds exist with stones alone.
The case is solid Everose gold with the fluted bezel cut into the metal itself. The dial is slate, a mid-grey with a sunray finish sweeping between light and near-black as the wrist turns, and it is the only cool surface on the watch. A sunray finish is cut into the dial as fine lines radiating from the middle, so the sweep is a property of the surface itself rather than of anything applied to it, which is why the effect survives at every angle and in every light. Ten Roman numerals in gold stand around it with an eleventh at six enlarged well past them and set with eleven diamonds. A sunray ground behaves differently under a set marker than a flat one does: the surface behind the stones is constantly changing value while the stones themselves hold a fixed brightness, so the enlarged six appears to move relative to its own background as the watch turns, and the numeral is alternately the brightest and the darkest element on the dial without changing at all. That is the specific effect this combination produces and it is not available on the flat grounds the reference builds. 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, since no solid gold Datejust at this size is built with a Jubilee or an Oyster. Between a cut rim, a sweeping dial and a ring of polished links, almost every surface on the watch is doing something with the light, and the eleven stones at six are the only fixed point among them. That is the reverse of the usual arrangement on a set dial, where the stones are the moving element and the ground holds still.
Hours, minutes, running seconds and a date changing in one step at midnight. 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 use a movement built for the larger diameter and not shared downward. The date sits at three under a magnifying lens, and against a mid-grey ground it is visible without dominating, which places this dial between the rose grounds, where the window is the brightest thing on the face, and the darker ones, where it competes with everything. The marker arrangement is what the configuration is for. Ten numerals name their own positions and the enlarged six fixes the bottom of the dial, so the watch is read from six upward rather than by position alone, and on a ground whose value is never constant that fixed starting point is worth more than it would be on a still surface. The alternative on this ground is applied markers with no stones at all, which this reference also builds, and between the two the difference is not decoration but whether the dial has an anchor. A sunray ground changes which parts of the dial are legible from moment to moment as the wrist moves, and a fixed enlarged numeral is the only element that stays put through all of it.
Slate is one of the broadest grounds the catalogue makes, reaching 31mm, 36mm, 37mm, 40mm, 41mm and 42mm, and its marker treatment changes at nearly every size. At 36mm and 41mm it takes a Roman set with a plain baton at nine that belongs to this ground alone across the entire range. At 31mm it takes applied markers when plain and the oversized six when set, on the six Everose references in both cases and on no yellow or white gold one; dark grey occupies that side of the size instead, in both of the arrangements slate takes here. Within this reference slate appears twice, plain and set, which chocolate also does in two set arrangements, and only rose appears more often. It is one of nine grounds across eleven configurations, seven of them carrying stones, which makes this a predominantly set reference rather than a plain one. The reference is one of five solid gold Datejusts at this size, all President-only, and 278285RBR is the same case under a set rim with an identical roster. Slate is one of two grounds at this reference the catalogue offers both plain and set, rose being the other, while white is never set and four further grounds appear only with stones. Its set version takes the large Roman six that aubergine and chocolate also carry.
This suits a buyer who wants a set dial that is not warm. Every other stone-carrying ground on this reference is either the alloy's own color or a shell taking the alloy's color from its surroundings; slate is the one that stays cool under the diamonds, so the watch has a genuine temperature contrast without any of it looking like a decision to be colorful. The eleven stones gathered at six keep the rest of the surface clear, which suits a sunray ground better than an even ring would, since the sweep is the thing worth seeing. Anyone who wants the ground without stones should take the plain slate, built here with applied markers. Anyone who wants the same arrangement warmer should take the chocolate, which is the other ground locked to this alloy in this treatment. And anyone who wants stones at the rim as well should take 278285RBR, which builds this identical dial under a rim set all the way round.
