The Sarpaneva Lunations Black Ruthenium

Independent Finnish watchmaker Stepan Sarpaneva is a selenophile, an erudite way to describe somebody who is obsessed with the Moon. Working from his Helsinki atelier in an old cable factory, Sarpaneva has created a microcosmic universe of watches bearing his signature moon face. However, his watches are far more than poetic odes to our neighbouring satellite and feature Sarpaneva’s hyper-precision calibre (Moonment) that tracks the cycles of the Moon with a single day of error once every 14,000 years. His latest Lunations watch interprets the darker side of the Moon with its black ruthenium-coated plates and bridges.

Since childhood, Sarpaneva has been fascinated by the Moon and its gravitational pull two days before the full Moon keeps him up all night. Following his studies at Wostep, Switzerland and work experience in some of the leading Swiss watch brands, Sarpaneva returned to Finland in 2003 to find his own voice – if you are interested in his career, don’t miss this exclusive interview. His ambitious in-house Moonment project, which began in 2011, differs from most moon phase complications because the movement is built around the complication, not the other way around.

Most moon phase complications rely on a wheel with 59 teeth to recreate the 29.5 days (29 days 12 hours 44 minutes 2.80 seconds)of a synodic month and need to be corrected by one day every two and half years. By increasing the gear ratio, precision is increased to achieve spectacular levels of accuracy, like Andreas Strehler’s Sauterelle à Lune Exacte, which requires a one-day correction in 2,060,757 years! Not surprisingly, Sarpaneva reached out to Strehler to help him calculate the gearing of his Moonment. Adjusted to 29 days, 12 hours, 44 minutes and 2.3 seconds, the Moonment only needs a one-day adjustment every 14,000 years.

The Sarpaneva Lunations, recently revisited in the more colourful Harvest Moon edition, returns in 2023 with a darker personality. The distinctive shape of Sarpaneva’s case, with its scalloped 6-sided bezel, short lugs and crown at 4 o’clock, is crafted from high-grade Outokumpu supra 316L/4435 steel and has a diameter of 42mm and a thickness of 9.8mm. User-friendliness has also been factored into the equation, and the two-part crown, decorated with Sarpaneva’s moon face and 12 short protruding rays, is used to set and wind the time and adjust the moon’s phases.

An openworked matte black ruthenium-coated plate reveals parts of the inverted movement, including the exposed balance wheel, and features Sarpaneva’s signature moon face at 6 o’clock. The large moon face in relief is laser engraved, filled with a cross-section of optical fibre and finished by hand. The two moons on the reverse side of the case are illuminated with RC Tritec Lumicast to appear white in daylight and emit a blue, orange or purple glow in the dark. As they enact the lunar cycles, the luminous moons cast an eerie glow on the dial’s moon’s face to indicate the precise phase of the Moon.

In a departure from other Sarpaneva Lunations models, the applied and skeletonised chapter ring bearing the indices has been removed, allowing an even better view of the movement. The hour and minute hands can be ordered in pitch black, red gold, flame blue or rhodium coated.

The reverse side reveals the orbiting twin moons fitted with an arrow that alights on a scale to indicate the precise age of the Moon in days. Placed on top of the luminescent base, each moon is decorated with the profile of Sarpaneva’s moon face. Echoing the skeletonised plate on the dial, the movement’s bridges are also treated with a matte black ruthenium coating. The Moonment is manual winding; it beats at 21,600vph and can store up to 60 hours of power reserve.

Availability & Price

A limited edition of 10 pieces, the Sarpaneva Lunations Black Ruthenium retails for EUR 39,500 (excl. tax). Delivery time is estimated between 4 – 12 months. For more information and to place an order, please consult studiosarpaneva.com.