What makes a Patek a Patek?

Patek Philippe Calatrava 18K Watch
Model: 5196R
Movement: Mechanical manual wind, 18 Jewels
Caliber: 215 PS
Case: 18K Solid rose gold
Diameter: 37mm (approximately 39mm with crown)
Thickness: 8mm
Dial: Brushed silver
Features: Gold hands and hour markers, seconds subdial at 6:00
Weight: 58g
Band: Original Patek Philippe alligator strap, 18k gold buckle
Lug Width: 21mm
Crystal: Sapphire, scratch resistant
Depth Rating: 30m/100ft
Crown: Push/pull
Includes: Patek Philippe inner and outer boxes, no papers
Condition: Excellent, light signs of case wear, strap has wear
Retail Price: $19,400