Jacob & Co. Pastel Arlequino: 54 diamonds on the balance wheel

In the Brilliant Flying Tourbillon Baguette Pastel Arlequino, Jacob & Co. sets 54 brilliant-cut diamonds directly onto the balance wheel. This transforms—of all components—the very part whose mass, moment of inertia, and precise balancing play a decisive role in determining the timekeeping of a mechanical watch into a decorative element. The new automatic caliber JCFA02 combines the diamond-set balance wheel with a flying tourbillon and a micro-rotor.

Diamonds on the regulating mechanism

The balance wheel, together with the balance spring, forms the regulating mechanism. It controls the energy output of the escapement and thus the rate of the movement. Even slight changes in its weight or weight distribution can affect the watch’s timekeeping. Setting gemstones on this component is therefore considerably more challenging than setting them on a bridge, a rotor, or a case.

Jacob & Co. refers to it as the first diamond-set balance wheel in modern watchmaking. According to the brand, historical precursors already existed in the 1820s and 1830s in Swiss and French pocket watches with cylinder escapements. However, the requirements for timekeeping accuracy at that time were significantly lower.

In the new design, the balance wheel—set with 54 brilliant-cut diamonds—oscillates at 3 hertz. At the same time, the flying tourbillon completes one revolution every 60 seconds. The interplay of these two movements continuously alters the angle at which the diamonds reflect light, creating the impression of a moving halo of light around the regulating mechanism.

366 Sapphires in Pastel Shades

The name “Pastel Arlequino” refers to the 366 sapphires distributed across the case, dial, crown, and clasp. Green, blue, lavender, pink, and other light hues do not blend into one another in a gradient but are arranged side by side in a deliberately alternating sequence. The name refers to the diamond-patterned costume of Arlecchino from the Italian Commedia dell’arte.

The stones are invisibly set: prongs or metal beads remain hidden beneath the surface. The 42-millimeter-wide and 11.61-millimeter-high white gold case is set with 194 sapphires and 32 baguette-cut white diamonds. The crown is set with twelve additional baguette-cut sapphires and one white diamond.

New JCFA02 Automatic Caliber

The newly developed JCFA02 caliber combines a flying tourbillon with a micro-rotor. It operates at 21,600 vibrations per hour and offers a 72-hour power reserve. The sapphire crystal case back reveals the bridges set with 234 brilliant-cut diamonds. Together with the 54 gemstones on the balance wheel, the gemstone setting thus extends to the movement side as well.

Technical Specifications

• Model: Brilliant Flying Tourbillon Baguette Pastel Arlequino
• Case: 18-karat white gold
• Diameter: 42 millimeters
• Height: 11.61 millimeters
• Movement: Jacob & Co. JCFA02 automatic caliber
• Regulation: flying 60-second tourbillon
• Frequency: 21,600 oscillations per hour, or 3 hertz
• Lift: Micro-rotor
• Power reserve: 72 hours
• Gemstone setting: 366 sapphires in pastel shades, 54 brilliant-cut diamonds on the balance wheel, and 234 brilliant-cut diamonds on the bridges

Between Watchmaking and Haute Joaillerie

The key aspect of this innovation is not the sheer number of gemstones, but their placement. With its diamond-set balance wheel, Jacob & Co. directly intervenes in the architecture of the regulating mechanism. The watch thus combines the decorative appeal of haute joaillerie with a design in which every additional ounce of weight must be technically accounted for.