Arnold & Son recently announced a new, stainless steel version of its HM Perpetual Moon timepiece — first introduced at Baselworld 2013 — with a beautiful, blue, lacquered guilloché dial.

To give a little background, the Arnold & Son Royal Collection is inspired by the timepieces created in the early part of watchmaker and brand namesake John Arnold’s life and pays tribute to the watches he produced for King George III and members of the British royal court.

According to the company, the moon-phase indication of the HM Perpetual Moon, seen on the majority of the upper half of the dial, is not only one of the biggest moon-phase displays on the market,  it is also one of the most accurate, “with only one day’s deviation every 122 years – at which point a single push on the corrector will keep it in sync for another 122 years.”

To make this oversized moon-phase display possible, right behind the aperture is a disk measuring 29 mm, with two hand-engraved moons measuring 11.2 mm each, along with stars and a blue lacquered guilloché surface matching the dial.

Further, around back, to set the moon-phase, there is a second moon-phase indication with eight phases of the moon; this is used to more easily, and precisely, set the function on the front.

From the technical side, not only is the HM Perpetual Moon incredibly precise, it is also an intriguing complication in that it is not simply a module added to the movement, but is, in fact, fully integrated into the caliber.

The case is 42 mm in diameter and crafted in stainless steel, which makes it both more affordable and lighter than the previous precious-metal versions. The fully polished case features stepped sides that are wide on the top and taper towards the wrist. A convex sapphire crystal with double anti-glare treatment protects the dial, and a sapphire on the back protects the movement side and offers a view of the immaculately finished mechanical components.

A double barrel allows for a maximum power reserve of 90-hours.

The dial is simple yet it boasts an exquisite construction, consisting of blue lacquered guilloché work, and it is punctuated with faceted, applied indexes (with no tips) and dots that represent the minutes, with large, polished, sword-shaped hands to indicate the time.

The Arnold & Son HM Perpetual Moon (Ref. 1GLAS.U02A.C122S) is paired with a black  hand-stitched alligator strap; its water-resistance is 30 meters. The retail price is $17,200.