Arnold & Son announced a 28-piece limited edition of the Perpetual Moon timepiece with a new dial material.

Introducing the Arnold & Son Perpetual Moon Obsidian — featuring a rare dial made from golden obsidian stone (sourced from Mexico) that gives off a sheen that’s similar to the 42 mm diameter 18K red gold case. The bronze-hued stone dial is contrasted by the rhodium-plated sword-shaped hour and minute hands and matching diamond-polished white gold hour markers.

“This volcanic stone has been mined in Central America since time immemorial and was known to have been used by pre-Columbian civilizations in their religious ceremonies. Obsidian has a very high silica content, making this material both hard and highly reflective,” according to Arnold & Son.

A dark blue lacquered moon phase disc is mechanically engraved with a wavy guilloché pattern surface and embedded with engraved rhodium-plated moon motifs and applied silvered stars which present the current moon cycle through the prominent ax-shaped aperture at the top of the dial. The 29 mm opening represents one of the largest moon phase displays on the market.

Driving the hours, minutes, and moon phase is hand wound caliber A&S1512 which is finely finished with sunray striping and chamfered and polished edges on the bridges, perlage on the mainplate, and a snailing pattern on the ratchet and winding wheels. Most notably, this is a double moon phase movement and the backside, visible through a clear caseback, has a special second moon phase display with the 4 major and 4 minor phases of the moon, controlled by the crown which allows you to set the display on the dial side via the visual display on the backside.

Arnold & Son’s caliber A&S1512 movement was entirely developed, produced, decorated, assembled, and adjusted in the brand’s manufacture in La Chaux-de-Fonds, Switzerland. This caliber beats at 3Hz and features double barrels, providing 90 hours of power reserve. The moon phase display of this movement will remain accurate for 122 years before deviating from the actual lunar cycle by one day.

The Perpetual Moon Obsidian limited edition comes paired with a blue alligator leather strap with visible silver-colored topstitching. (Ref. 1GLAR.Z01A)

Retail is $35,100.