The Code 11.59 collection launched in 2019 representing Audemars Piguet's most significant new design language since Royal Oak's 1972 debut—a controversial statement given Royal Oak's iconic status but accurate assessment of Code 11.59's ambition. Where Royal Oak defined integrated bracelet sports watch category, Code 11.59 pursued different territory: round dress watch with hidden complexity, classical proportions concealing technical innovation, refined elegance targeting collectors seeking Royal Oak alternatives. The initial reception proved divisive: some appreciated multi-part case architecture and sophisticated finishing, others criticized perceived deviation from Royal Oak heritage or questioned necessity of second major collection. Yet Code 11.59 persisted, expanding complications catalog through perpetual calendars, tourbillons, minute repeaters—establishing legitimacy through mechanical depth rather than immediate aesthetic acceptance. The 2025 introduction of Caliber 7138 perpetual calendar (replacing Caliber 5134 that traced lineage to 1967 Caliber 2120 ultra-thin base) brought next-generation mechanics to Code 11.59: crown-only adjustment eliminating corrector pushers, integrated single-layer construction replacing modular architecture, 50-hour guarantee versus previous movement's more modest reserve. The 2026 reference 26443NB debuts Caliber 7139—the openworked evolution of 7138—marking Code 11.59's first perpetual calendar with skeletonized movement visible through sapphire dial, establishing haute horlogerie credentials through mechanical transparency previously reserved for limited editions.
The 41mm x 10.6mm case employs Code 11.59's signature multi-part construction: round 18k white gold bezel and caseback sandwiching octagonal black ceramic case middle—architecture creating visual complexity absent from conventional round cases. From dial-on perspective, the watch reads as purely round dress watch: circular bezel flowing into domed sapphire crystal, no geometric angles interrupting classical proportions. Yet side profile reveals architectural depth: the octagonal ceramic middle (echoing Royal Oak's octagonal bezel geometry) creates faceted surfaces between round bezel and caseback, beveled transitions defining material boundaries. This hidden octagon represents Code 11.59's conceptual bridge between Royal Oak heritage and dress watch refinement—acknowledging brand DNA while pursuing distinct aesthetic territory.
The white gold bezel receives polished finish creating bright reflective surface, while black ceramic middle employs satin-brushed texture creating matte contrast. The case lugs extend from ceramic middle rather than bezel, integrating with ceramic structure and receiving identical brushed finishing. The black ceramic crown at 3 o'clock operates Caliber 7139's crown-only adjustment system—four positions controlling winding (position 0), calendar adjustment via bidirectional rotation (position 1), unused intermediate position, and time setting (position 3). Water resistance extends 30 meters—modest rating reflecting dress watch positioning and openworked movement requiring careful sealing.
The caseback employs sapphire crystal secured by white gold outer ring, revealing Caliber 7139 from rear perspective. The sapphire receives glareproof treatment (anti-reflective coating) improving movement visibility despite ambient lighting conditions. The movement architecture visible through caseback displays openworked bridges, skeletonized base plate, pink gold-toned components contrasting against rhodium-plated elements—decorative treatment creating visual hierarchy emphasizing specific mechanical elements.
The dial employs transparent sapphire crystal revealing Caliber 7139 beneath—no traditional dial plate obscuring movement, instead allowing complete visibility of perpetual calendar mechanism. Four subdials display complications: day subdial at 9 o'clock showing three-letter abbreviations (MON/TUE/WED etc.) with 24-hour indicator ring and red-marked non-correction zone warning, date subdial at 12 o'clock displaying numerals 1-31, month/leap year subdial at 3 o'clock showing month abbreviations and four-year cycle, astronomical moonphase at 6 o'clock employing aventurine disc simulating night sky with gold moon tracking 29.53-day lunar cycle (accuracy requiring correction once per 122 years).
The subdials feature smoked transparent treatment: grey gradient shading from clear center to darker periphery maintaining legibility while revealing movement beneath. This transparency represents critical design decision: the subdials must remain sufficiently opaque ensuring complication reading despite underlying mechanical complexity, yet transparent enough justifying openworked architecture rather than employing solid dial obscuring movement completely.
Applied 18k pink gold hour markers—rhodium-toned rectangular batons at each hour position—affix to inner bezel ring rather than dial plate (which doesn't exist). The rhodium treatment creates grey metallic appearance coordinating with smoked subdials while pink gold base adds warm undertone visible under certain lighting. The 18k white gold hands receive luminescent filling enabling nighttime legibility, faceted construction creating multiple reflective surfaces improving visibility against mechanically complex background.
The black inner bezel—angled ring between subdials and case—displays week numbers 1-52 in white printing, indicated by dedicated hand sweeping dial periphery once weekly. The minute track prints in white along outermost edge providing chronometric reference. The overall dial composition balances mechanical transparency (openworked movement creating visual depth) against functional legibility (smoked subdials, contrasting hands, clear printing ensuring complications remain readable).
Audemars Piguet's Caliber 7139 represents openworked evolution of 2025's Caliber 7138, both drawing on RD#2 research project producing world's thinnest automatic perpetual calendar. The movement measures 29.6mm diameter x 4.1mm thickness—remarkable considering integrated perpetual calendar mechanism, automatic winding system, and decorative openworking all within single-layer construction rather than stacked modular architecture.
The perpetual calendar integration represents key technical achievement: previous Code 11.59 perpetual calendars employed Caliber 5134 (itself evolution of Caliber 2120 base with perpetual calendar module added above), requiring corrector pushers adjusting individual displays. Caliber 7139 integrates all functions within movement's primary layer: 48-tooth program wheel pre-programmed with month lengths across four-year leap year cycle, date mechanism, day mechanism, month mechanism, leap year mechanism, moonphase mechanism all coexisting with timekeeping train at same vertical level.
The crown-only adjustment operates via four positions: position 0 (fully pushed) for automatic winding, position 1 (first pull) for calendar adjustment with bidirectional rotation (clockwise advances date, counterclockwise advances month/leap year simultaneously), position 2 unused, position 3 (full pull) for time setting with stop-seconds halting balance wheel. The system eliminates corrector pushers penetrating case (improving water resistance) and simplifies perpetual calendar operation—owners need not memorize pusher functions or locate corrector stylus, instead performing all adjustments via familiar crown interface.
The openworked architecture removes maximum material from bridges and base plate while preserving structural integrity: each bridge features calculated geometry retaining material only along load paths, creating skeletal framework supporting gear train while allowing light penetration from dial and caseback simultaneously. The pink gold-toned components (barrel bridge, balance bridge, oscillating weight) create warm metallic contrast against rhodium-plated grey wheel train, establishing visual hierarchy guiding eye through mechanical complexity.
Movement finishing meets manufacture standards: Côtes de Genève striping on bridges, circular graining on base plate, polished bevels, anglage (hand-beveled corners), polished screw heads. The openworked execution demands flawless finishing as every surface remains perpetually visible—imperfections cannot hide beneath dial coverage or solid bridges.
The watch mounts on black alligator leather strap with traditional square-scale embossing, secured by 18k white gold three-blade folding clasp. The strap employment (versus integrated bracelet) positions watch firmly within dress watch category—leather suggesting formal contexts, precious metal clasp maintaining luxury positioning, absence of integrated bracelet differentiating from Royal Oak's sports watch DNA.
The reference 26443NB occupies pioneering position within Code 11.59 collection: first openworked perpetual calendar establishing haute horlogerie credentials, Caliber 7139 demonstrating Audemars Piguet's perpetual calendar innovation extending beyond Royal Oak into dress watch territory, white gold/black ceramic two-tone case creating contemporary alternative to monochrome precious metal construction. The watch appeals to collectors seeking Code 11.59 identity without Royal Oak comparison, those valuing perpetual calendar complication presented through mechanical transparency, and enthusiasts appreciating crown-only adjustment system simplifying traditional perpetual calendar operation.
The openworked dial creates engagement impossible with solid dials: owners observe perpetual calendar mechanism advancing date at midnight, watch month wheel stepping forward end-of-month, see leap year cam rotating through four-year cycle. This transparency transforms complication from abstract function into observable mechanical process—the perpetual calendar becomes educational demonstration rather than hidden mystery. The smoked subdials maintain practical legibility while the sapphire dial enables mechanical appreciation, balancing usability against horological transparency.
