Edouard Koehn Legacy Moonphase Chronograph Purple USA Limited Edition

Edouard Koehn, the independent Swiss manufacture based in La Chaux-de-Fonds, has announced the release of the Legacy Moonphase Chronograph Purple USA Limited Edition. This release represents a calculated expansion of the brand’s presence in the North American market, a region historically significant to the company’s namesake founder. Limited to a production run of exactly ten individually numbered pieces, this reference combines a high-frequency chronograph complication with a classic moon phase indicator, packaged within a 40mm stainless steel chassis. The timepiece serves as a modern reinterpretation of the mechanical standards established by Edouard Koehn during his tenure as a director and shareholder at Patek Philippe in the late 19th century, before he established his own workshop in 1891.

The rationale behind a United States-exclusive edition is rooted in the brand's archival history rather than mere market segmentation. During his career, Edouard Koehn traveled extensively to North America to establish distribution networks for high-grade Swiss horology, viewing the region as a critical frontier for mechanical precision. This modern release, therefore, acts as a horological homage to those early trans-Atlantic endeavors. The choice of a "Purple USA" theme introduces a distinct aesthetic variable to the Legacy collection, utilizing a gradient dial execution that departs from the traditional monochrome palettes often associated with classical complications. By strictly limiting production, the manufacture aims to maintain a high ratio of exclusivity for collectors focusing on independent Swiss horology.

The Case and Dial

The watch is housed in a 316L stainless steel case measuring 40mm in diameter, a dimension that strikes a balance between vintage dress proportions and modern sports-chronograph presence. The case architecture features polished lugs that curve downward to hug the wrist, providing a structural counterpoint to the rounded case flanks. A critical dimension to note is the thickness: the case body itself measures 12.90mm, but the total height rises to 14.10mm when accounting for the crystal. This additional height is attributed to the "glass-box" domed sapphire crystal, a component designed to mimic the profile of vintage acrylic plexiglass crystals found on mid-century chronographs. Unlike acrylic, however, this double-sided anti-reflective sapphire offers significant scratch resistance while allowing light to flood the dial from oblique angles, enhancing the visibility of the perimeter tracks.

The dial of this limited edition is the primary differentiator, featuring a gradient purple hue that transitions from a lighter, more vibrant violet at the center to a deep, nearly black purple at the periphery. This fumé effect is overlaid with a vertical satin finish, a technique that creates linear light reflections running from twelve to six o'clock, contrasting sharply with the concentric "snailed" finish of the subdials. The time is indicated via applied Breguet numerals, a typographic choice that reinforces the classical design language. These numerals are polished to catch the light against the matte texture of the vertical brushing. The leaf-shaped hands (feuille) for the hours and minutes are rendered in a silver tone, while the central chronograph seconds hand and the sub-dial hands introduce a metallic blue accent, aiding in legibility and differentiating the timing functions from the running time.

The layout of the dial follows a modified tri-compax arrangement, though it technically functions as a two-register chronograph with additional complications. The running seconds are positioned at 9 o'clock, balancing the instantaneous 30-minute chronograph counter located at 3 o'clock. At the 6 o'clock position, the manufacture has integrated a dual-function subdial displaying both the date and the moon phase. The date is indicated by a small hand circling the subdial, encompassing a central aperture that reveals the moon phase disk. This integration allows for a symmetric dial architecture, preserving the vertical balance often disrupted in chronographs that utilize a 6-9-12 layout. The moon phase itself is a classic representation, featuring a blue sky with silvered stars and moon, adding a layer of astronomical tracking to the short-interval timing of the chronograph.

The Movement

Powering the Legacy Moonphase Chronograph is a self-winding mechanical movement developed in collaboration with Manufacture Concepto, a specialized movement constructor in La Chaux-de-Fonds. This caliber is exclusively modified for Edouard Koehn to meet specific architectural and finishing requirements. The mechanism operates at a standard high-beat frequency of 4Hz, or 28,800 vibrations per hour, which is essential for a chronograph intended to measure elapsed time with precision to one-eighth of a second. The movement relies on a chronometer-grade regulating organ, implying that the balance wheel and hairspring have been adjusted to tight tolerances to ensure isochronism and positional stability, crucial for maintaining accuracy when the chronograph complication is engaged.

The chronograph mechanism features an instantaneous 30-minute counter. Unlike a semi-instantaneous or dragging counter where the minute hand creeps forward slowly as the seconds hand approaches the 60-second mark, an instantaneous counter jumps precisely to the next minute marker the moment the seconds hand crosses zero. This mechanical behavior requires a specific cam or snail profile to build up energy and release it instantly, eliminating ambiguity when reading elapsed time. The integration of the moon phase adds further complexity to the gear train. The display is driven by a 59-tooth wheel, which corresponds to two full lunar cycles (29.5 days x 2). The disk advances one tooth every 24 hours, providing a faithful representation of the waxing and waning moon, requiring correction only after extended periods of operation.

Visually, the movement is showcased through a sapphire crystal caseback, revealing a level of finishing consistent with the brand's positioning. The rotor is skeletonized to allow for an unobstructed view of the bridges below and features a laser-engraved or stamped logo. The bridges are decorated with Côtes de Genève (Geneva stripes), while the base plate exhibits perlage (circular graining). The use of blued screws throughout the movement serves both an aesthetic and functional purpose, historically used to harden the steel and prevent oxidation. With a power reserve of 60 hours, the watch can be left stationary for over two days—a standard weekend—without stopping, a practical feature for a manual-wind or automatic chronograph in a rotation of multiple timepieces.

The Strap

Completing the aesthetic package is a strap manufactured from Louisiana alligator leather. The exterior is finished in a matte anthracite grey, a neutral tone that grounds the vibrant purple of the dial. The strap construction features large, square scales, indicating that the leather was sourced from the premium belly section of the hide rather than the tails or flanks. A subtle yet significant detail is the lining of the strap, which is rendered in purple alligator flank leather. This matching purple lining is a discreet nod to the dial color, visible only to the wearer when the watch is unbuckled, emphasizing the bespoke nature of this limited edition.

The strap is secured to the wrist via a stainless steel folding clasp, which minimizes wear on the leather compared to a traditional pin buckle by reducing the need to bend the strap at a sharp angle during fastening. The choice of a folding clasp also adds a measure of security, preventing the watch from slipping off the wrist while being put on or taken off. The lug width and attachment points are standard, allowing for potential strap changes, though the integration of the stock strap with the curved lugs suggests it was designed as a cohesive unit. The strap’s color and texture are critical components in the overall visual weight of the watch, balancing the 40mm steel case and ensuring the purple dial remains the focal point without overwhelming the overall design.

Pricing and Availability

The Edouard Koehn Legacy Moonphase Chronograph Purple USA Limited Edition is priced at $14,800 USD. This pricing positions the timepiece in a competitive segment of the luxury market, occupied by both established heritage manufactures and high-end independents. The value proposition relies heavily on the exclusivity of the 10-piece production run, the modified Concepto caliber with chronometer-grade regulation, and the intricate finishing of the dial and case.

As indicated by the nomenclature, availability is restricted to the United States market. The low production number suggests that allocation will be handled directly through Edouard Koehn’s authorized network or direct-to-consumer channels focusing on North American collectors. Each piece is individually numbered on the caseback (e.g., "01/10 PE"), verifying its place within the limited series. This release continues Edouard Koehn’s strategy of producing small-batch, mechanically dense timepieces that leverage the brand’s historical legitimacy while utilizing modern manufacturing partnerships to deliver reliable, serviceable high-complication watches.

Technical Specifications

Case: 316L Stainless Steel, 40mm diameter, 12.90mm thick (14.10mm with crystal)

Movement: Self-winding mechanical chronograph, developed with Manufacture Concepto

Dial: Gradient Purple with vertical satin finish, applied Breguet numerals

Strap: Anthracite Louisiana alligator leather with purple alligator-flank lining

Price: $14,800 USD

Notes: Limited Edition of 10 pieces; Water resistant to 50m; 60-hour power reserve