Produced around 1965, perfectly proportioned at 35mm, this elegant 18ct yellow gold gents Calatrava, ref. 3429 represents everything that we love about Patek Philippe. 60 years ago, its hand-finished movement was the pinnacle of watchmaking technology. Yet its style and restraint are something that watches even now struggle to emulate. 

The screw-down case-back (by Geneva maker Edouard Wenger) was designed to keep the movement hermetically sealed. The small seconds, silver opaline dial and discreet baton hands discreetly veil the phenomenal movement within. 

The movement, cal. 27-460, is one the great self-winding calibres of the 20th century, part of a trio produced by Patek Philippe. It succeeded their famous cal. 12'''-600, preserving its best parts and improving the rest. Notably, this watch has a free-sprung Gyromax balance – elimination of the swan's neck index for better precision. It has a solid 18ct gold winding rotor, grained and emblazoned with a fabulous deeply-cut Calatrava emblem, all mounted on a large durable ball-bearing. This is an improvement on the simple ruby bushing of its predecessor. 

Naturally, Patek retained the elegant and efficient twin-pawl winding system, mesmerising to watch as it gently oscillates. The 27-460 was eventually succeeded by the also-revered calibre 240 with micro-rotor, still in production today. 

Huber and Banbury's Patek data indicate that 6,900 of these movements were made, but this was spread over 16 models in 10 years. Further research suggests that between 1961 and 1969 fewer than 1,000 ref. 3429J were produced. There are USA export marks on the bridge ('HOX'), and the Geneva Seal, indicating the extreme quality of these mid-century movements.

With only around 100 of these watches made per year, this Calatrava is a must-have.