Two shell dials sit four variants apart on this reference and they occupy opposite ends of the collection. Black mother-of-pearl appears on six references, all of them 31 mm, all containing yellow gold, all carrying one arrangement. White mother-of-pearl appears on sixteen references at this size alone, across solid Everose, solid white gold, solid yellow gold and all three steel and gold constructions, and continues from 28 mm through 40. Same material, same working, same ring of settings, and one is the most widely offered stone-set ground the collection makes while the other is the most confined. This variant is the broad one, in a case of steel and yellow gold, under a fluted bezel, on an Oyster bracelet.
At 31 mm the ground carries the identical treatment on every case that receives it. Every one of the sixteen references takes a ring of diamonds in gold settings with no numeral among them, whether the case is solid Everose, solid gold, platinum-free two-tone or anything else the size offers, and no construction earns an addition or a variation. That is unusual on a reference where silver, dark grey and olive green are each offered in two set arrangements and the buyer chooses between them. Shell is given one and the question does not arise. The gold of this construction sits in the fluted bezel, since fluting is never cut into steel, and the case sides, lugs and bracelet are steel throughout. There is a further reason the ring suits shell better than any alternative would. A numeral has to be placed somewhere specific on the dial, and on a natural material the surface at that position is different on every disc, so the same numeral would sit against bright nacre on one example and against a dull section on the next. The settings avoid that by being distributed evenly around the perimeter, where the shell is at its most consistent and where no single position carries the arrangement.
The material accounts for the uniformity. Shell is cut from a natural disc, sliced thin and laminated onto a metal plate, and the surface it produces is already doing what a marker arrangement would otherwise be added to supply, refracting light through its laminations and returning it broken into pale colors that shift as the wrist turns. Adding a numeral would compete with that and, worse, would sit against a background that differs from one example of the reference to the next. The ring at the perimeter avoids both problems. The plate beneath is pierced at each hour position and nowhere else, which matters because the disc is bonded across its whole area rather than seated at its edge and follows any deviation exactly. The movement is built to the 31 mm case, self-winding, holding close to 55 hours off the wrist against roughly 70 at 36 mm. The aperture is the one place the material is cut rather than merely pierced beneath, and it is the hardest part of the assembly. Opening a window through laminated shell without chipping the edge is a different operation from cutting one in a metal plate, and the edge then has to be finished so it reads as intentional rather than as damage. On a dial whose appeal rests on an unbroken natural surface that single opening at three is the only visible interruption, and how cleanly it is executed decides whether the dial looks made or merely assembled. It is also the detail that separates a well-executed shell dial from a poor one, and the reason the material appears on relatively few brands rather than being widely adopted. Cutting the disc is straightforward; finishing the aperture through it consistently, across every example of sixteen references, is the part that takes an established process.
What separates the two shells is not the material but where the collection has chosen to put them. White reaches every case size from 28 mm to 40 and every material except plain steel; black reaches one size and one metal family. They are worked identically, set identically and finished identically, and a buyer looking at both on this reference is looking at the same idea offered under two entirely different distribution rules. Nothing in either listing indicates which of the two is the common ground and which is the scarce one, and the difference is a matter of catalogue policy rather than of the watches themselves. That distinction is worth holding onto when scarcity is being weighed. A ground confined to six references is scarce because the collection decided to confine it, not because the material is harder to obtain or the dial harder to build, and the two shells on this reference are the clearest demonstration available: identical process, identical treatment, one offered almost everywhere and one almost nowhere. Mother-of-pearl is one of five grounds at this reference that exist only in set form, and it takes diamond hour markers in gold settings, the treatment six of the seven grounds here share. The large Roman six is confined to dark grey, olive green and silver.
The argument for this configuration is that it gives the least predictable dial in the collection the widest possible choice of case. A buyer who wants white shell can have it in almost any metal at almost any size and will find the same ring of settings waiting on each, so the case decision and the dial decision come apart entirely. Very few grounds allow that. The Oyster keeps the watch flat and unassuming beneath a surface that will not match any other example of the reference, and among the arrangements offered here it is the one where the specification says least about what will actually arrive. Two examples of this reference on a counter will differ visibly from one another, and neither will resemble the photograph that sold them, which is a strange property for a watch to have and the reason the ground keeps its following. It is also the arrangement that makes the least sense to buy unseen and the most sense to buy in person, which is an unusual thing to be able to say about a watch this widely available.
