Introduction:

This Patek Philippe 2552J "Disco Volante" automatic Calatrava.  The watch was made in 1955, and  made in 18K yellow gold. The watch measures 36mm in diameter, powered with an 12-600 caliber 30-jewel automatic movement, #761356;  case # 687905 The watch is further accompanied with a alligator strap and Patek gold buckle.

Essay:  Patek Philippe introduced the reference 2552 in 1954 and discontinued it in 1960. This model is one of the few references that house the automatic caliber 12-600 AT. These models feature a thick stepped round bezel, hence the nickname "Disco Volante," or flying saucer.  The 2552 is among those Patek Philippe references blessed by the caliber12-600AT, the first automatic movement by Patek Philippe, universally considered one of the most outstanding automatic movement ever developed and an absolute example of industrial art. The most famously housed in reference 2526, this movement is the result of a momentous technical effort. Suffice to say that the first automatic Patek Philippe was released some twenty years after the first automatic Rolex, but the wait was well rewarded.  The architecture and size of this movement allow for particular positioning of the gears and for a relatively large balance wheel, for increased accuracy. The massive 18K rotor is ideal for capturing energy and its lavish finish betrays the care and attention Patek Philippe reserved to this caliber. The watch movement is known for its accuracy due to is larger balance wheel.  
The 2552 was available in the three gold colors and in platinum, for a total estimated output of around 650 pieces. Which make only about 100 watches a year.
There are only about 65-70 known from the market.