Obsidian may very well be one of the most evocative materials on earth. Its dark color is so iconic that the word “obsidian” itself might as well be a synonym for black. Not all types of this glassy volcanic substance are black, however, and for its latest release, Arnold & Son has focused on a rare lustrous variety from Mexico. The limited-edition Arnold & Son Perpetual Moon Obsidian pairs a massive, finely detailed moonphase display with a dial made from dramatic golden obsidian, creating one of the most striking and memorable moonphase designs on the current market.

Arnold & Son renders the 42mm case of the Perpetual Moon Obsidian in 18k 5N red gold. While somewhat oversized for such a dressy design, the case itself is simple, combining classical elements like a narrow polished bezel and small stepped lugs. A matching stepped case side architecture looks in initial images to visually break up the 11.4mm case thickness somewhat, while a domed sapphire crystal reinforces the classical charm of the design.

Undoubtedly the most eye-catching portion of the Arnold & Son Perpetual Moon Obsidian’s design is the main dial, coated in a fine layer of crushed golden obsidian. With a unique chemical makeup and a dramatically different look to more common black obsidian, golden obsidian has a history in Mexican and Mesoamerican jewelry making and religious artifacts dating back centuries before Columbus. In images, it looks to give off a slightly muted, glittery look, with sharp flakes of differing tones giving texture to the base layer. Arnold & Son contrasts this golden surface with cooler colors through the rest of the dial design. The handset, pointed applied indices, and applied minutes track are all rhodium-plated, as is the edge of the massive moonphase window. The moonphase complication itself uses a delicate guilloché base in midnight blue, along with more rhodium for the stars and the oversized, deeply textured moon. The effect is far from subtle, but handsome and undeniably luxe.

Inside the Arnold & Son Perpetual Moon Obsidian beats the in-house A&S1512 hand-wound moonphase movement. Thanks to an oversized mainspring barrel, the A&S1512 boasts a hefty 90-hour power reserve at a steady 21,600 bph beat rate. The greatest draw for this movement, however, is the moonphase complication itself, which Arnold & Son claims will remain accurate to within one day every 122 years.

To complete the gold and blue colorway of the rest of the design, Arnold & Son finishes the Perpetual Moon Obsidian with a matching midnight blue alligator leather strap with hand-finished silver-tone contrast stitching. This classical strap option looks in images to pick up the cooler tones of the dial well, creating a harmonious look.

With an opulently unique dial treatment and a regal colorway, the limited edition Arnold & Son Perpetual Moon Obsidian is an eye-catching operatic take on one of the brand’s signature designs. Only 28 examples of the Arnold & Son Perpetual Moon Obsidian will be made, available now through authorized dealers at an MSRP of 31,900 CHF. For more details, please visit the brand’s website.