This post is for lovers of Jaeger Le-Coultre as much as it is for admirers of Patek Philppe . When in 1970. Patek needed an ultra thin automatic mechanism for their new Calatrava, they went to no other than to JLC. The Jeager Cal 920 was in production since 1967 and was a movement of choice for both Audemars and Vacheron Constantin.
Patek engraved the movement and renamed it to calibre 28-255.
It was a beauty! A mere 2.45mm thin - including the carousel gold rotor - this was one of the best engineered slim-line automatic movements on the market. It proudly featured the number of 'only JLC can make this' and features: a free sprung Gyromax balance, 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 - just to list a few details.
The 36 jewel movement is adjusted to heat, cold and isochronysm in 5 positions. Finely decorated, it is both eye-pleasing and quiet on the wrist. And thanks to JLC, for next 30 years, Patek was able to deliver an ultra slim Calatrava to aficionados of fine watches.
The Ref. 3590 is an 18K white gold version which is just 6.5mm thick.
Pictures below are provided for your enjoyment :-)