Skip to content



Back to WISe Art


The Astronomia is the epitome of 21st century haute horlogerie and a globally recognized symbol of Jacob & Co watchmaking expertise. A world-first both in the boldness of its unprecedented concept and its entirely mechanical construction, the Astronomia has gone beyond impressive horological achievements and has been regarded as an outstanding multidisciplinary engineering achievement.

The Astronomia Sky introduces new complications of celestial inspiration to Astronomia: a sidereal display, vertical month display, zodiac signs, day and night indication, as well as a celestial panorama, orbital second indication and a Jacob-Cut® diamond Moon have all been added to fully transform the iconic Astronomia. Full of unparalleled watchmaking solutions and adorned with exceptional finishing techniques, the Astronomia Sky is a poetic and singular entity in ultra-high-end watchmaking.


The Astronomia Sky stays true to the original layout of the Astronomia’s iconic caliber construction: the entire four-arm assembly of its Exclusive JCAM11 Caliber rotates, a truly unprecedented engineering and watchmaking achievement that is as spectacular, as challenging it is to realize. Its four rotating arms and the complications they carry all float through the space between its front sapphire crystal and blued Titanium celestial dial.

The four arms of the Astronomia Sky carry the gravitational triple-axis tourbillon that is the timekeeping organ of the watch, the orbital, double-axis, vertical seconds indication, an exclusive Jacob-Cut® 1-carat diamond, and a differential-leveled time display. This four-arm assembly completes a rotation around the center of the watch in 20 minutes. Another outstanding feature of the Astronomia Sky is how each pair of opposing arms are perfectly calculated counterweights of one another – a testament to peerless materials engineering and watch movement design. By having equal weights on these opposing arms, its axles are relieved from strain and increased pull, as the movement takes up different orientations in space.


Whereas the tourbillon was originally invented to be a single-axis, rotating cage to carry the regulating organ of a mechanical pocket watch for improved timekeeping performance, the Astronomia Sky brings this 224-year-old invention to breathtaking levels of modern refinement and complexity.

The triple-axis tourbillon of the Astronomia Sky is at the forefront of ultra-high-end watchmaking. Its delicately decorated cage encapsulates the balance wheel, hairspring, escape wheel and a number of other crucially important components. Characterized by this openworked cage, this exotic tourbillon rotates on three axes simultaneously. It is a constellation of superbly finished components that, when assembled and fine-tuned expertly, allows the JCAM11 to keep accurate time throughout its 60-hour power reserve.

A full rotation on the 1st axis takes exactly 60 seconds, as a nod towards the traditional single-axis tourbillon. The 2nd axis of rotation requires 5 minutes to complete, while the 3rd axis of rotation is made possible by the 20-minute, four-arm rotating platform of the Astronomia Sky. This makes for a bold new look at how tourbillons can function, when engineered with cutting-edge, ultra-modern technologies and timeless horological heritage in mind.


At the center of the movement, a lacquered hand-engraved titanium globe rotates on itself in 24 hours, inside a tinted half-domed sapphire crystal, showing night and day.


The Astronomia Sky brings a host of uniquely executed astronomical complications into the extremely complex world of Astronomia. Apart from the day-night indication that works as a shield around the globe in the center of the dial, these features are implemented on the Celestial Dial that is spread out behind the four rotating arms.

A view on the celestial vault through zodiac signs can be admired in hues of mesmerizing blue and gold: this delicately patterned dial makes a full rotation in exactly one sidereal year. On the periphery of this indication are the twelve months, turning this into a month display of unprecedented elegance and complexity. Over the blue Celestial Dial the oval sky indication is located: with its moving oval outline it shows the portion of the stars visible from the Northern hemisphere at any given time.


The Jacob-Cut diamond starts out as a much larger rough diamond. First, a rough diamond big enough has to be found, and the purity, clarity, and color has to be of the highest quality both inside and out, and there can be no inclusions. If they start to cut the diamond and find an inclusion, the entire piece will be ruined.

Next, the diamond is cut by machine into a round shape, close in size to the final diamond.

Then, the gem cutter shapes the stone by hand, cutting each individual facet (of 288). This has to be done slowly and carefully, as the stone has to be perfectly round and symmetrical. The danger is that the stone will become oblong and not round. To be used in the Astronomia Collection, the Jacob-cut diamond has to be completely round and weigh exactly as much as the other three satellites (time display, triple-axis tourbillon, magnesium globe).

During the process, if the gem cutter puts slightly too much pressure while adding the facets, too much of the diamond will be cut away, and the ball will end up smaller than the desired diameter. The cutting process takes at least two weeks of dedicated, painstaking work.

To make the final one-carat, Jacob-cut diamond with 288 facets, more than half of the initial rough diamond will be cut away.

The complexity of cutting the 288 facets by hand and making sure everything is symmetrical and the diamond is absolutely round, is what makes the Jacob & Co. diamond used in the Astronomia collection so special.


The Astronomia Sky’s case measures 47 millimeters in diameter and 25 millimeters thick between the highest point of its specially curved front sapphire crystal and the lowest point of its case. Its 18K Rose Gold case holds a single-piece sapphire crystal window around its periphery, allowing for unhindered viewing of the spectacular caliber inside. One’s focus on the universe that lives inside the Astronomia Sky is further assisted by the openworked lugs – a minute, yet important detail that drives ones vision towards the center of the timepiece.


The time display sub-dial of the Astronomia Sky is driven through an infinitesimal differential system that allows it to always remain levelled and hence perfectly legible, even as the movement’s four-armed platform performs its continuous, 20-minute orbit. The Roman numerals on the skeletonized dial are hand-engraved and filled with black lacquer, while the hand-finished hands appear in gun blue metallic.


In the past, setting an astronomical watch has been laborious, and often involved making a trip to the watchmaker to set it correctly. To make things easier, Jacob & Co. has created a simple yet ingenious solution to the time setting of this complicated watch. The company created a simple app for smartphones that determines where you are in the world, then guides you through the setting of the watch. The Astronomia Sky has two lift-out bows and two notched wheels on the back of the watch, making time setting very easy for the user. One bow is for setting the time and the day/night indicator (both based on 24-hour solar time), while the other bow is for winding the mechanical movement. One wheel is to set the sidereal time, while the other wheel is to set the oval sky indicator – and you will be guided through the setting process by the app.


Iconic gravitational triple-axis tourbillon

47mm 18K rose gold and sapphire crystal case, with sapphire crystal back

All four satellites constantly turn around the dial in 20 minutes

288-facet Jacob-cut diamond turning in 60 seconds

Magnesium globe turning in 60 seconds

Unique differential always keeps the time display in the correct 12/6 orientation, no matter where it is the rotation

Celestial Vault showing the constellations of the Northern Hemisphere, making one full rotation in one sidereal year

Oval Sky Indicator showing the constellations overhead at any given time, making one full rotation in one sidereal day

Domed and curved, anti-reflective sapphire crystal

Unique crown-less design; winding and setting lift-out bows on the case back

Specially designed application to make setting simple and easy