SPECIFICATIONS

Brand: Patek Philippe
Model: Golden Ellipse
Reference Number: 3634J
Movement: Automatic
Condition: Very good (worn with little signs of wear)
Gender: Men’s
Time Period: 1977 
Box: Yes
Papers: Extract from the Patek Philippe Archives

THE CALIBER

Caliber: 28-255
Jewels: 36

THE CASE

Case Material: 18K yellow gold
Case Diameter: 38 x 33.5 mm
Thickness: 6 mm
Waterproof: -
Bezel Material: Fixed stepped 18K yellow gold 
Glass: Mineral 
Caseback: Solid
Dial: Black plain onyx 
Dial Numerals: No numerals 

THE BRACELET / STRAP

Bracelet Material: Black Leather
Buckle: Ardillon 
Buckle Material: 18K yellow gold 

THE FUNCTIONS

Hours, minutes, 38-hour power reserve

FURTHER READING

Two-piece oval-shaped brushed and polished case
18K yellow gold applied dauphine-shaped hour/minute hands 
Cabochon onyx set crown
18K yellow gold solid case back, snap-on back
Concealed T-bar style lugs
The caliber 28-255 is an automatic movement, rhodium-plated, with fausses côtes decoration, a straight-line lever escapement, a free-sprung gyromax balance, a solid gold rotor on a beryllium carousel supported at four jeweled rollers, a ball bearing intermediate wheel in the auto winding system and a jeweled ratchet under its own bridge, a self-compensating balance-spring shock absorber and adjusted to heat, cold, isochronism and five positions. Stamped with the Seal of Geneva.
This mechanism oscillates at the frequency of 19,800 vph (2.75 Hz).
This caliber was also used on the Patek Philippe Nautilus ref. 3700.
This caliber was based on the JLC 920 Ebauche and was one of the best engineered slim-line automatic movement on the market.
Original Patek Philippe leather strap.
Visible sharp hallmarks on the side of the case. 
Complete (with Patek Philippe fitted box and extract from the Patek Philippe archives dated 1977).