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The Encyclopedia of Horology

Wristwatch · Rectangular wristwatch

Patek Philippe Ref. 521 'Staybrite' Stainless Steel Art Deco Wristwatch

Partially verified

This Art Deco rectangular wristwatch, reference 521, was manufactured by Patek Philippe in 1937 according to the auction house. Housed in a stainless steel 'Staybrite' case measuring 23 mm wide and 40 mm in overall length, the watch features stepped case flanks attributed to Geneva case maker Wenger. The two-tone silvered dial displays applied steel Art Deco numerals, an outer railway minute track, and a subsidiary seconds register at 6 o'clock. The source documents it as powered by a manual-wind caliber 9'''90 movement numbered 831'717, fitted in case number 615'482.

Frontal view of the rectangular Patek Philippe reference 521 in stainless steel with stepped flanks and two-tone silvered dial.
Frontal view of the rectangular Patek Philippe reference 521 in stainless steel with stepped flanks and two-tone silvered dial. — Christie's. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
onlineonly.christies.com
Category
Wristwatch · Rectangular wristwatch
Maker / attribution
Patek Philippe
Reference
521
Catalogue / lot identifier
106
Source-reported date
1937
Country
Switzerland
Source-reported serial
831'717

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Case Construction

This reference 521 wristwatch features a stainless steel 'Staybrite' case, measuring 23 mm in width and 40 mm in overall length. The case design incorporates stepped lateral sides and was produced by the Geneva case maker Wenger.

The case has undergone historical repolishing and exhibits surface scratching commensurate with its age. The inside of the upper case is punched with the last two digits of the case number, '82'.

Evidence for this section
  • “CASE MATERIAL: Stainless steel”
  • “CASE SIZE: 23 mm. wide, 40 mm. overall length”
  • “Its case was made by Wenger, one of the best Geneva case makers of the period.”
  • “The case has been repolished at some time in the past, light surface scratching and wear commensurate with age, the inside of the upper case is punched with the last two digits of the case number ‘82’.”

Dial Composition

The timepiece features a two-tone silvered rectangular dial with applied steel numerals. Subsidiary seconds are indicated at the 6 o'clock position.

Records indicate the dial was previously cleaned and refinished. The varnish coating has deteriorated, resulting in a patchy appearance, though the numerals and hard enamel features appear original.

Evidence for this section
  • “DIAL: Silvered two-tone”
  • “The dial has been cleaned and refinished at some time in the past and the varnish coating has now deteriorated so that it has a ‘patchy’ appearance, the numerals and hard enamel features appear to be original.”

Mechanical Specifications

The watch is powered by a manual-wind caliber 9'''90 movement, identified by number 831'717. The movement was reported to be in working order at the time of cataloging.

No independent accuracy testing was performed. Due to the age of the timepiece, professional servicing is recommended.

Evidence for this section
  • “CALIBER: 9’’’90”
  • “MOVEMENT NO. 831'717”
  • “The movement is in working order at the time of cataloguing, consistent with the age of the watch. The movement has not been tested for accuracy. A service is recommended.”

Open research questions

  • What specific documents from the Patek Philippe archives provide the basis for the 1937 manufacture date versus the 1938 sale date?
  • Are there additional technical specifications available for the caliber 9'''90 regarding service intervals for this reference?

Source evidence

Recorded claims and source quotations for Patek Philippe Ref. 521 'Staybrite' Stainless Steel Art Deco Wristwatch
FieldSource-reported valueSource quotation
Reference521“REF. 521”
Movement Number831'717“MOVEMENT NO. 831'717”
Case Number615'482“CASE NO. 615'482”
Manufacture Date1937“MANUFACTURED IN : 1937”
Caliber9'''90“CALIBER: 9’’’90”
Case MakerWenger“Its case was made by Wenger, one of the best Geneva case makers of the period.”
Case Dimensions23 mm wide, 40 mm overall length“CASE SIZE: 23 mm. wide, 40 mm. overall length”
Archive DocumentationExtract from the Archives“Patek Philippe Extract from the Archives confirming manufacture of the present watch with silvered dial, raised steel indexes in 1937 and its subsequent sale on 8 September 1938”

Visible details

  • Rectangular stainless steel case with stepped, fluted lateral case sides.
  • Two-tone silvered rectangular dial with applied metallic numerals (12, 3, 9) and baton indices.
  • Subsidiary seconds dial located at the 6 o'clock position.
  • Brown exotic leather strap fitted to the watch with visible grain patterns.

Research qualifications

  • The case back and internal movement caliber 9'''90 are not shown in the provided photograph.
  • Source notes the dial was cleaned and refinished in the past, with deteriorated varnish causing a patchy look, and the case was previously repolished.
  • The display strap shown in the photo was not included in the sale and was replaced upon transfer.

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

PATEK PHILIPPE, STEEL ‘STAYBRITE’ ART DECO RECTANGULAR WRISTWATCH WITH TWO-TONE SILVERED DIAL, REF. 521, MOVEMENT NO. 831'717, CASE NO. 615'482 | Christie’s

Reviewed 2026-10-22 · Record 90e20b5700

Terms in this record

Glossary explanations for terms named in this object’s record.

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