Patek Philippe Golden Ellipse 18K Yellow Gold Onyx Dial Ref. 3634J

DETAILS
Manufacturer: Patek Philippe
Model: Golden Ellipse
Reference Number: 3634J
Movement: Automatic
Condition: Very good (worn with little signs of wear)
Gender: Men’s/Unisex
Time Period: 1977 
Retail / Compare-At Price: n/a collector's item
Our Best Price: $10,500 

CALIBER
Movement: -
Caliber: 28 - 255
Jewels: 36

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

BRACELET / STRAP
Bracelet color: Black
Bracelet Material: Leather
Clasp: Ardillon Patek Philippe Ellipse
Clasp material: 18K yellow gold 

FUNCTIONS
Hours, minutes, 38-hour power reserve

OTHERS
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 auto winding system and a jeweled ratchet under it's 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).