This is the diamond-set version of the 38.5 mm Royal Oak Concept flying tourbillon, and it is the reference the rest of the group should be read against. The openworked white gold dial and inner bezel are set with brilliant-cut diamonds, which is the classical choice, and the interesting decision is what happens at the clasp: it is set with brilliant-cut blue sapphires rather than diamonds. That single substitution is the whole character of the watch. A fully diamond-set piece would have been uniform and slightly anonymous. Putting a colour in the one place only the wearer sees turns it into something private. The case is white gold, 38.5 mm across and 11.4 mm thick, and the strap is blue alligator. It is no longer part of the current collection.
The case measures 38.5 mm across and 11.4 mm thick in white gold, which is unusually slim for a tourbillon and is the reason this reference gets worn rather than kept. White gold is the correct metal for a diamond setting because the two share a colour temperature, so the stones extend the metal rather than sitting on it, and the dial reads as one continuous bright surface rather than as a field with things attached. The dial is openworked white gold set with brilliant-cut diamonds. Openworking a dial that is also being set compounds two problems into one, because every aperture cut for the mechanism removes metal a stone might have been seated in, so the setting cannot be designed first and applied after. It has to follow the openwork, and the pattern of stones is dictated by whatever the movement beneath has left available. The inner bezel is set to match and carries the brightness to the edge of the dial. The hands are openworked white gold, skeletonised so they cross the mechanism without concealing it. The strap is hand-stitched blue alligator in a large square scale, coarser than dress-watch hide and correctly matched to the Royal Oak case, closed with a white gold folding clasp set with brilliant-cut blue sapphires. A blue rubber strap with a constellation decoration is supplied alongside, and the two straps put the same watch in genuinely different registers rather than offering a change of colour. The clasp is worth one more line, because a folding clasp on a set watch is not the neutral choice a pin buckle would be. It keeps the strap in a closed loop, so the watch is never opened out fully to be put on and the set surfaces are handled less often as a result. It also distributes the weight of a precious metal case across a wider span of the wrist, which on a slim watch is what stops it rolling. And because the same clasp travels between both supplied straps, the sapphires go wherever the watch goes.
The movement carries a flying tourbillon and a power reserve display, with hours and minutes. A flying tourbillon is supported from beneath only, with no bridge crossing the top of the rotating carriage, so the assembly appears unsupported and stays fully visible from the dial side. That is why it is paired with an openworked dial here, and the two are really a single decision: the dial is opened to show the tourbillon, and the tourbillon is built flying so there is something uninterrupted to show. The power reserve display is the practical complication, reporting how much running time remains before the watch stops. On a tourbillon that is worth more than it would be on an ordinary watch, since a movement of this kind left to run down has to be restarted and reset rather than simply picked up, and the indicator is read against the openworked mechanism rather than from a panel of its own. There is no date, no chronograph and no seconds display, which on a dial that is both openworked and set is necessity rather than restraint.
Within the Royal Oak Concept collection this belongs to the gem-set flying tourbillons at 38.5 mm, a small group distinct in intent from the large technical Concept references. Those are 44 mm titanium watches carrying repeaters and chronographs, read as engineering exercises and bought as such. This group takes the collection name into a case a third smaller and spends the budget on setting rather than on complication count. Its direct siblings substitute blue sapphires or multicoloured stones for the diamonds across the dial and bezel, and the 26228 references alongside use baguette-cut stones rather than brilliant. Against all of them this is the version that reads most conventionally, which is exactly why the sapphire clasp matters: it is the one element that stops the watch being the obvious choice in the group.
This reference suits a collector who wants the classical setting and does not want the watch to be entirely predictable. Diamonds on white gold is the combination that will always be legible as luxury, and the blue sapphires at the clasp are the correction to it, placed where nobody but the owner encounters them. That is a specific kind of taste and it tends to belong to buyers who have already owned something more obvious. The slimness is the practical argument for the reference. At 11.4 mm this is a tourbillon that fits under a cuff, which most are not, and it is the reason a watch of this complexity ends up in regular rotation. Now that the reference has left the catalogue the production is closed, and gem-set tourbillons at this size are made in the smallest quantities Audemars Piguet produces. The buyer is someone who wants the mechanism and the setting to be equally serious.
