The reference 5170P-001 is the watch in which Patek Philippe's most significant movement development of the contemporary period — the Calibre CH 29-535 PS, the manufacture's first fully in-house chronograph caliber — appears in the material and chromatic configuration that most directly honors the development's importance: platinum case, blue sunburst dial fading to black at the edges, nine baguette-cut diamond hour markers, and the hand-winding format whose choice reflects the classic chronograph's architectural tradition rather than the convenience of automatic winding. The 5170P is now discontinued, produced in a short production run that the secondary market has recognized as one of the defining characteristics of this reference's specific collector significance: the CH 29-535 PS in its platinum expression, on a blue-to-black gradient dial with baguette diamond markers, in a 39-millimeter case whose dimension connects to the classical chronograph proportions of the twentieth century's most celebrated wristwatch chronographs.
The Calibre CH 29-535 PS is the movement whose introduction with the 5170J (the yellow gold first reference in the 5170 family) was the most consequential Patek Philippe movement announcement of the decade following the 5004's production. Patek Philippe's first in-house chronograph movement, renowned for its technical sophistication and reliability, the CH 29-535 PS represents the conclusion of a development process through which Patek Philippe brought the chronograph mechanism — previously produced in collaboration with Lemania and Valjoux-based architecture in various Patek applications — entirely into the manufacture's own domain. The caliber comprises 269 parts across 11 bridges with 33 jewels, operating at 28,800 vibrations per hour and providing 65 hours of power reserve from the hand-wound mainspring. The column wheel governs the start, stop, and reset sequence with the precision that the pillar-and-lever architecture consistently provides; the specific construction of the CH 29-535 PS's column wheel and the lever geometry that translates the wheel's positions into the chronograph's operational states are elements whose refinement across the movement's development at Patek is documented in the manufacture's own production records. The Patek Philippe Seal — the manufacture's own certification standard, more demanding than the Geneva Seal and specifically requiring adjustment to six positions and a precision tolerance more rigorous than COSC — certifies the CH 29-535 PS's finishing and precision in the movement's entirety.
The bicompax dial layout — small seconds at nine o'clock and thirty-minute chronograph counter at three o'clock, with no twelve-hour counter — is the specific register arrangement that distinguishes the 5170 family's chronograph architecture from the tricompax layout of the 5172 and other three-register Patek chronograph references. Two-register chronographs are a personal favorite among collectors. It stands out from the normal layout in the specific sense that the bicompax's two-register simplicity produces a more visually resolved dial than the tricompax at equivalent case size: the two subdials' positions at nine and three create the visual balance across the dial's horizontal axis without the visual crowding that a third register at six o'clock introduces in a 39-millimeter case. The blue sunburst dial's gradient — a dark blue sunburst pattern that fades to black around the edges — produces the specific dial treatment whose visual character deepens from the brighter, more vivid blue at the center toward the near-black at the perimeter, the gradient making the two white subdial registers at nine and three read with particular clarity against the perimeter zone's darkest expression of the gradient.
The nine baguette-cut diamond hour markers are the dial's gemological program, their combined weight of 0.23 carats distributed across the nine applied positions — twelve o'clock through six o'clock and nine o'clock through three o'clock, with the nine and three occupied by the subdial registers rather than by individual markers. The highlights are the nine baguette-cut diamonds that function as markers. Patek Philippe makes it more subtle than just screaming diamonds — the markers are integrated with restraint. The baguette cut's step-cut elongated rectangular facet architecture presents each stone's interior depth in the controlled directional manner specific to the step-cut: each hour marker's color and clarity visible in the specific long rectangular reflections that the baguette's step facets produce, the markers' cool colorless precision reading against the blue-to-black gradient ground with the understated precision that the 5170P's design brief consistently pursues. Against platinum — the cool, slightly diffuse brilliance of the polished 950 platinum case — the baguette markers' own cool colorless quality reads in the same temperature as the surrounding case, the stones' precision continuous with the case's own cool precious material rather than providing a warm-contrast element.
The platinum case at 39.4mm diameter and 8.5mm height carries the 5170P's specific case proportions in the Calatrava-influenced round case architecture whose lugs and case profile belong to the classical dress watch tradition. The knurled platinum crown provides the winding and time-setting engagement for the hand-wound CH 29-535 PS. Water resistance is 30 meters through the sapphire exhibition caseback whose transparency reveals the movement's eleven-bridge architecture, the column wheel's position accessible for observation through the caseback glass.
The black alligator leather strap with platinum fold-over clasp completes the reference in the strap format whose formal dress watch character is consistent with the 5170P's design register: a leather strap whose black tone is continuous with the dial's own dark perimeter zone, the fold-over clasp providing the secure deployment in the most precious metal consistent with the case's own platinum material. Water resistance is 30 meters.
The 5170P's discontinued status — the 5170P was made in a very short production run and is now discontinued by Patek Philippe — positions it in the category of Patek Philippe references whose production cessation concentrates the secondary market's attention in the way that ongoing production does not. For the collector whose approach to Patek Philippe's chronograph production is organized around the CH 29-535 PS's mechanical significance — the first in-house Patek chronograph caliber — the 5170P-001 in platinum with blue sunburst gradient dial and baguette diamond markers is the configuration in which that significance is expressed in the most materially complete and most chromatic format the reference family produced.
