At Baselworld 2017, Rolex was not only plumbing the depths with its 1,220-meter-water-resistant Sea-Dweller; it was also casting its gaze heavenward at the moon and stars with the newest model in its elegantly appointed Cellini collection, the Rolex Cellini Moonphase — a watch that features a patented, astronomical moon-phase function, a meteorite-appliqué moon, and an Everose gold case.

The 39 mm case is made from Everose Gold

Incidentally, Rolex has never produced a moonphase after the Ref. 6062 made in the Forties. A rare Ref. 6062 recently was in the news and is expected to be the most expensive Rolex sold at an auction soon. The 39-mm case of the Rolex Cellini Moonphase is made from Everose gold, a proprietary alloy that mixes gold, copper, and a touch of platinum, and sports a polished finish.

It features the double-domed, fluted bezel that is a hallmark of the Cellini collection, a domed, solid screw-down caseback; a domed sapphire crystal with non-reflective coating on both sides; and a screw-down crown for a water-resistance of 60 meters.

Its white lacquered dial — swept over by rose gold hands and punctuated by rose-gold hour appliqués — opens up at the 6 o’clock position to reveal a blue enameled disk displaying the full moon (represented visually by a round fragment of rhodium-plated meteorite applied to the disk), the new moon (represented by a thin, silver ring), and a field of stars.

The moon is a rhodium-plated meteorite applied to the disk

The pointer at the 12 o’clock position on this subdial points tothe correct moon-phase as the two moons rotate through the lunar cycle. Along with the phase of the moon (and the time), this watch displays the date with a crescent-tipped blued hand pointing to a 1 -through-31 scale printed around the dial’s circumference.

A wristshot of the Cellini MoonphaseThe movement driving all of these functions is Rolex’s manufacture Caliber 3195, with a patented module for the moon-phase indication, which is engineered to be astronomically accurate for 122 years.

The self-winding movement has 31 jewels, oscillates at a frequency of 28,800 vph, and carries approximately 48 hours of power reserve when fully wound. It features numerous Rolex-developed technical innovations, including a paramagnetic blue Parachrom hairspring with Rolex overcoil and a high-performance Paraflex shock-absorption system.

The Rolex Cellini Moonphase — somewhat astoundingly, the first Rolex watch with a moon-phase produced since the 1950s — is mounted on a brown alligator leather strap, with Rolex’s adjustable folding “Crownclasp” in 18k Everose gold to match the case.

Like all Rolex watches since 2015, it is covered by the brand’s Superlative Chronometer certification, indicating that the fully assembled watch has passed a battery of tests of its precision, power reserve, water-resistance, and self-winding efficiency.

The final cased watch is guaranteed an accuracy of -2/+2 seconds per day, a rate more than twice what is required of a COSC-certified chronometer. The watch is priced at $26,750 and carries an international five-year guarantee.