The special 288-facet Jacob-Cut diamond is a feature of the Astronomia collection. There is only one vendor in the world that can produce this patented cut and it are based in Israel. Here are the steps in its creation:
The spherical Jacob-Cut diamond starts out as a circular rough diamond. First, a rough diamond big enough must be found, and the purity, clarity, and color have to be of the highest quality both inside and out, and there can be no inclusions. If an inclusion is found in the cutting process, the gem must be replaced.
Next, the diamond is cut by machine into a round shape, near the size to the final weight of the diamond, which is usually 1 carat.
Then, the gem cutter shapes the stone by hand, cutting each individual facet (of 288). This must be done slowly and carefully, as the stone must be perfectly round and symmetrical. The danger is that the stone will become oblong. To be used in the Astronomia Collection, the Jacob-cut diamond must 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 desired. The cutting process takes at least two weeks of dedicated, painstaking work.
To make the final 1-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 Flawless Diamond Round is a rare timepiece in this collection because it has two Jacob-Cut diamonds. The first is the 1-carat diamond that is being carried on one of the, which is standard on nearly all Astronomia watches. The second is a massive 2.88-carat light yellow diamond that is positioned on top of the Astronomia four-arm vertical movement.