Take the numerals away and the color becomes the subject. Reference 278243 is the 31mm Datejust in a combination of stainless steel and yellow gold with a domed yellow gold bezel, and this configuration carries an olive green dial set with diamond markers and no numerals at all, on the Oyster bracelet. On the Roman version of the same ground a full sequence covers a considerable share of the dial and the color shows through in the gaps, and here twelve stones occupy a fraction of that space, so the olive runs almost uninterrupted from the center out to the marker ring. This is the greenest the reference gets.
That difference is more consequential than a marker change usually is, because the amount of visible ground is what determines how much a colored dial reads as colored. The lacquer is applied in several thin coats to keep the tone even across a curved surface, opaque and holding one value regardless of angle, and olive sits at the mid-point of the model's tonal range with enough brown in it to meet a warm metal partway rather than opposing it. Against that ground the diamonds carry moderate contrast, so they punctuate the color rather than competing with it, which is the opposite of what the same stones do on the dark grey dial where they are the brightest thing present. The markers stand slightly proud of the surface and Rolex keeps the settings low and tight, since a raised marker on a 31mm dial has little room before it starts to crowd the hands. Steel and yellow gold is the most visible two-metal pairing Rolex makes, since yellow gold sits nowhere near steel in color and every junction between them reads as a clear boundary. The steel forms the case and the outer bracelet links while the gold takes the domed bezel, the crown, the bracelet center rows and the marker settings, and the gold is solid rather than plated or capped. The bracelet is the Oyster, three broad flat links brushed across the top with polished flanks, tapering toward the clasp so the weight sits forward on the wrist. The date sits at three under the Cyclops lens on a matched disc, its frame polished gold and set level with the surface. Rolex also matches the height of the marker settings to the height of the date frame, 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.
Rolex matches the date disc to the dial rather than leaving a paler window in a colored surface, and a single aperture also keeps the marker ring uninterrupted, since a second would break a pattern that depends on running continuously. 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 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, and the Oyster closes with a concealed clasp folded away inside the links. Correction takes seconds and requires no tool. Hand winding runs through the same crown, and the watch takes to being worn better than to being rotated, since a smaller rotor gathers less from the same amount of movement.
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. Rolex registered the name for its steel and gold construction in 1933, on the reasoning that steel supplies the structure and gold supplies the color. Green reached the Rolex catalogue broadly over the past decade and came to this model later than most colors, which is why the olive configurations still read as current where champagne has settled into the range. Within the generation, 278243 is the steel and yellow gold reference with a domed bezel. Gem-set dials have been part of the model for most of its history, and the marker-only arrangement is the more common of the two forms Rolex offers here. Olive green is one of three grounds on this reference built in two set arrangements, alongside dark grey and silver, which gives each of the three four of the twenty-two rows the reference builds.
The buyer for this wants the color first and the stones second. Rolex builds olive two ways on the reference and the difference between them is not decoration but exposure, since the marker version leaves far more of the dial visible than the Roman version does, and anyone choosing between them is really deciding how much green they want to see. That is a more useful way to compare them than the marker style suggests. It is also the less formal of the two by some distance, since twelve stones impose no order the way a numeral sequence does, and buyers who want the watch to read as a colored watch rather than a set one arrive here. It is the version that will be described as the green one by everyone who sees it. Olive green is never offered plain here, and only champagne and white arrive unset at all.
