The Astronomia Sky Tourbillon has a beautiful dial comprised of a base celestial dial, covering the internal surface of the inside case, manufactured from a grade 5 blue Titanium with 18K gold hand-engraved and applied lovely stars and zodiacal signs constellations visible in the northern hemisphere. This needs one sidereal year to make a full rotation, showing, on the side, the 12 months indication. The stars visibility oval indicator, in gold, needs one sidereal day / 23.5640916 hours, to make a complete dial rotation.
The everyday time indication is done on a hand angled and polished titanium subdial, with lacquered indexes, that uses a differential gear system to keep it always in the correct viewer position and display the right time using hand finished blue minutes and hours hands.
In the centre of the dial there is a hand-engraved titanium globe, beautifully lacquered, and rotating on 2 axes: – a full rotation on its own axe in 24 hours – representing Earth’s revolution and a 20 minutes central axe, travelling across the celestial vault – a complete rotation of the entire movement.
Over the globe, there is a tinted half-domed sapphire, symbolising night and day and used as a 24 hours indication.
15 minutes clockwise from the time subdial there is the Orbital seconds’ indication which rotates on the central axe in 20 minutes and has a fixed hand indicating of the seconds on the open worked titanium wheel. On the other side of the Orbital seconds, there is the 1 carat, 288 facets patented Jacob-cut Orange sapphire which offers a spectacular view.
I must mention that all the elements are perfect weighted and balanced to have a symmetrical load on all the axes.
The spectacular Jacob&Co gravitational triple-axis tourbillon makes a rotation on the first axis in one minute, on the second axis of 5 minutes and on the third axis, together with all the elements, in 20 minutes.
This Astronomia Sky by Jacob&Co limited series of 18 pieces has a twin in white gold.
These spectacular timepieces come with an alligator leather strap and gold folding buckle.
Setting the Astronomia Sky is very simple due to the back “bows” and wheels. More explanation can be seen in the video bellow. The dynamic movement of the entire construction with a rotation in 20 minutes makes this watch very attractive at every point in time.
The movement is visible from the top and the sides: a hand wound 40mm diameter caliber with a height of 17.15 mm due to multiple elements. This movement uses 42 jewels from a total of 395 components and has a heart beating with a slow 3Hz or 21,600vph and a 60h power reserve. The main material used is titanium which is very light, resistant but very hard to work with. Still, the finishes present will make blush any steel or other alloy movements: the main plate and bridges have drawn flanks (etirage) and hand bevelled and polished edges with a circular graining (perlage) finish, polished sink and screws. The entire movement is a feast for the eyes.