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The Encyclopedia of Horology

Wristwatch · Perpetual calendar chronograph wristwatch

Patek Philippe Reference 3970 Perpetual Calendar Chronograph

Partially verified

This Patek Philippe Reference 3970 is an 18k yellow gold manual-winding perpetual calendar chronograph wristwatch featuring a silvery opaline dial. The dial layout includes day and month apertures beneath 12 o'clock, subsidiary dials displaying running seconds with a 24-hour indicator, a 30-minute counter with a leap-year cycle, and a date display with an integrated moon phase. Measuring 36 mm in diameter, the case features round chronograph pushers, stepped lugs, and interchangeable sapphire crystal and solid casebacks according to the source. The watch is powered by the 24-jewel caliber CH 27-70 movement, with movement number 875907 and case number 2873870.

Front view of the Patek Philippe Ref. 3970 perpetual calendar chronograph in 18k yellow gold on a leather strap
Front view of the Patek Philippe Ref. 3970 perpetual calendar chronograph in 18k yellow gold on a leather strap — Antiquorum. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
catalog.antiquorum.swiss
Category
Wristwatch · Perpetual calendar chronograph wristwatch
Maker / attribution
Patek Philippe
Reference
3970
Catalogue / lot identifier
129
Source-reported date
1991
Country
Switzerland
Source-reported serial
875907

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

Identity and Configuration

The Patek Philippe Reference 3970 is a manual-winding perpetual calendar chronograph. This 18k yellow gold example has a case diameter of 36 mm. It features a silvery opaline dial and was sold on October 2, 1991.

The watch is fitted with an alligator-pattern leather strap and an 18k yellow gold pin buckle. The auction documentation describes the case as unpolished, noting that the lug hallmarks are deep and the case angles are well-defined.

Evidence for this section
  • “18k yellow gold manualwinding perpetual calendar chronograph wristwatch”
  • “silvery opaline dial”
  • “Year sold on 2 Oct 1991”
  • “Diameter 36mm.”
  • “case retaining its sharp and well-defined angles”
  • “hallmarks stamped on the sides of the lugs remain exceptionally deep”

Mechanism and Movement

The timepiece is powered by the 24-jewel caliber CH 27-70 manual-winding movement, identified by movement number 875907. It features a transparent caseback, though the auction catalog states that an overhaul is recommended for the movement at the buyer's expense.

The movement, dial, and case are signed. The watch includes a moon phase indicator.

Evidence for this section
  • “Caliber CH 27-70, 24 jewels”
  • “Movement No. 875907”
  • “transparent caseback”
  • “Overhaul recommended, at buyer's expense”
  • “Signature dial, case and movement”
  • “moonphase indicator”

Provenance and Documentation

Included with the lot are several original items: a fitted presentation box, a Certificate of Origin dated October 2, 1991, an additional solid gold caseback, a push pin, and various booklets and leaflets. The lot is categorized as a 'Second Series' Reference 3970.

The watch was previously held by a collector based in Hong Kong.

Evidence for this section
  • “Certificate of Origin dated on 2 Oct 1991”
  • “PP fitted box”
  • “additional solid gold caseback”
  • “PATEK PHILIPPE, REF. 3970, PERPETUAL CALENDAR CHRONOGRAPH, SECOND SERIES”
  • “discerning Hong Kong-based collector”

Open research questions

  • What specific criteria define the 'Second Series' designation for the Patek Philippe Reference 3970 in the context of this serial number?
  • Does the 'Very good' movement grade explicitly detail the mechanical issues necessitating the recommended overhaul?

Source evidence

Recorded claims and source quotations for Patek Philippe Reference 3970 Perpetual Calendar Chronograph
FieldSource-reported valueSource quotation
Reference3970“Reference 3970”
Movement number875907“Movement No. 875907”
Case number2873870“Case No. 2873870”
CaliberCH 27-70“Caliber CH 27-70, 24 jewels”
Case material18k yellow gold“18k yellow gold manualwinding perpetual calendar chronograph wristwatch”
Diameter36mm“Diameter 36mm.”
Sale date2 Oct 1991“Year sold on 2 Oct 1991”
Case Number2873870“Case No. 2873870”
Weight70g (approx.)“Weight 70gr. (approx.)”

Visible details

  • Light silvery opaline dial with applied yellow-gold baton indexes and matching leaf hands.
  • Twin calendar apertures for day and month positioned directly below the 12 o'clock marker.
  • Round chronograph pushers flanking the winding crown at 2 and 4 o'clock.
  • Fitted brown alligator-pattern leather strap attached between stepped downward-curved lugs.

Research qualifications

  • Internal movement mechanism is not visible in the primary photograph.
  • The auction house catalog notes an overhaul is recommended at buyer's expense.

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

Consulted source

PATEK PHILIPPE, REF. 3970, PERPETUAL CALENDAR CHRONOGRAPH, SECOND SERIES, 18K YELLOW GOLD | Important Modern & Vintage Timepieces | Hong Kong May 31, 2026

Reviewed 2026-10-25 · Record 8656f55d63

Terms in this record

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

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