Unlike the trio of preceding Advanced Research watches which were all annual calendars, the Ref. 5550P is a perpetual calendar. The Ref. 5550P uses the silicon parts Patek Philippe developed and used in the earlier annual calendar watches. Using a modified cal. 240 QP, the 5550P has a GyromaxSi balance wheel with adjustable gold weights, Pulsomax escape wheel and pallet fork, as well as the Spiromax hairspring. All are made of silicon, and collectively termed ‘Oscillomax.

All that provides superior chronometry, thanks to improved geometry of the escapement and higher balance wheel inertia amongst other things, in addition to a 50% longer power reserve than the regular cal. 240 QP movement.

These watches are only just being delivered, and pictured here in all its glory is one of the first samples to hit retailers. The watch looks far better in the metal. The 37.2 mm platinum case has a good weight and seems larger than it is.

Like the Ref. 5350R Advanced Research annual calendar, the Ref. 5550P has a silvered dial with a vertical, brushed finish. The effect is subtle yet attractive; the gold hands and numerals complement the dial, which has a hint of grey, very well.

Instinctively I did not like the luminous hands and dots on the minute track when I first saw stock photos, but in reality the overall effect is pleasing. This is a very attractive looking watch. A big improvement over the earlier annual calendar models is the clean sapphire case back; the annual calendar watches had tacky looking text printed on the inside of the sapphire display back.

The movement finishing is of course impeccable, as is the case with top-end Patek Philippe models. Though this movement is not as clean as it should be.

Only 300 pieces will be made in an unnumbered limited edition. This retails for about 50% more than the regular Ref. 5140P perpetual calendar, which is extremely hefty. The intrinsic qualities of this watch – basically four silicon components – don’t just justify that premium.

But this is a limited edition and it is a Patek Philippe. So for collectors of Patek, especially those who already own the earlier Advanced Research, this is hard to pass up. Unsurprisingly, all of them are apparently spoken for already (by end clients and not retailers). Enjoy the rest of the photos below.

The diamond set in the case at 12 o’clock signifies the case is platinum

The Patek Philippe case hallmark

Pulsomax

GyromaxSi

Spiromax