The tourbillon opening is the darkest thing on this dial and the 5N gold is what draws your eye to it. That relationship between the two is effectively the whole composition. A platinum case and whitened guilloche silver give a cool, even field; the applied 5N gold elements are the only warm thing on the watch; and the carriage aperture is a hole in the middle of all of it with something moving inside. F.P. Journe built the Tourbillon Souverain this way from 1999 until 2003, at 38 mm and 9.9 mm deep, on the calibre 1498, hand wound, with the hours and minutes in a subdial at 3 o'clock and the power reserve at 10. It has not been made in this configuration since, and the movement was replaced rather than revised.
An aperture on a dial is a negative space and it has to be given an edge or it reads as damage. That is what the applied gold is doing here beyond decoration. The surround of the carriage opening, the ring of the time subdial and the markers are all made in 5N gold and fixed to the silver plate, standing proud of it and catching light from a different angle, so each of the three areas on the face is outlined rather than merely printed. Against a platinum case the warmth of that gold reads clearly without being loud, since 5N carries less copper than the 6N Journe uses elsewhere and sits closer to neutral. The effect is that the dial has a structure you can see even before you register what any of the parts do. Look at the same watch with white gold applied instead and the structure is still there but quieter; look at it with yellow gold and the structure shouts. Five N is the middle position of the three, and on a dial with a large dark opening in it that turns out to be the most comfortable place to be. The carriage remains the subject and the gold does the work of framing rather than competing.
Regulating a balance is difficult and regulating one inside a rotating carriage is considerably worse. F.P. Journe uses a free sprung balance, which means there is no index lever bearing on the hairspring and the rate is adjusted instead by four small weights threaded into the rim of the balance itself. On an ordinary movement that arrangement is more stable than an index because there is nothing to be knocked out of position. Inside a tourbillon it becomes close to essential, because the entire escapement assembly is turning once a minute and an index would be one more component subject to that rotation. There is a cost. Adjusting four weights on a balance that lives inside a cage means dismantling far more of the watch than turning an index would, so regulation on this movement is slow, skilled work rather than a quick correction. The whole assembly also has to be poised, meaning balanced about its axis, and a carriage that is out of poise will introduce exactly the positional error the tourbillon exists to remove. None of that is visible from the front, which is characteristic of this watch: the carriage turning in its aperture is the advertisement, and the reasoning behind how it is regulated stays out of sight. The calibre 1498 runs at 21,600 alternations per hour, on 28 jewels across 191 components, in a movement 32.40 mm across and 6.60 mm high.
Forty-two hours means winding it every day, and that is a real condition of ownership rather than a footnote. A tourbillon with a constant force device does not run for a working week the way an Octa does; it runs for not quite two days, and twenty turns of the crown fills it from empty. In practice this makes the watch a daily object or a stopped one, with very little middle ground. An owner who wears it Monday to Friday and puts it down on Saturday will find it stopped on Sunday. That is not a defect, and it is not fixable without making the watch thicker than 9.9 mm, but it does select fairly firmly for a particular kind of owner: somebody who wants a mechanical relationship with a watch rather than a passive one, who is content to wind it each morning, and who reads the reserve indication at 10 before deciding whether to. Journe put that indication on the dial for exactly this reason. On a five-day automatic an indication like that is a convenience. On a hand-wound tourbillon it is the one instrument that stops the watch from stopping, and it is consulted daily rather than occasionally.
Establish the movement generation before anything else, since the dial settles it on sight. A power reserve at 10 with no seconds subdial, in a 38 mm case, is the calibre 1498 and the years from 1999 to 2003. Confirm plated brass through the caseback and check the bridge edges for the plating wear this period develops, which cannot be corrected. Then examine the applied 5N gold against the platinum in daylight to confirm the two read as intended rather than as a mismatch from a replaced dial, and look at the edges of the applied elements for softening. Raking light across the whitened guilloche silver will show any refinishing at once. Wind it fully, twenty turns, and let it run down to confirm the indication tracks the descent. Have the carriage examined by a specialist rather than by a general watchmaker, and establish exactly who has serviced the watch and when, because a movement of this age has certainly been apart at least once and a constant force tourbillon is not forgiving of indifferent work.
