Patek Philippe first launched reference 591 in 1938. At the time of production, the model was entirely different from anything that the manufacture had ever produced. The case, produced by Wenger, featured "bean" shaped lugs, lovingly dubbed "Fagiolino", or "little bean". The angular, and relatively sharp lines starkly contrasted with the smooth Calatrava design of reference 130 and 533. Reference 591 was also larger than its chronograph siblings, boasting a 34 millimeter case diameter, giving the watch a modern aesthetic today.

Reference 591 was produced in exceedingly small numbers. In fact, it is the rarest production chronograph model that the firm produced throughout the 1930s and 1950s. Research suggests that less than 17 examples cased in yellow gold have appeared on the market thus far, with approximately 34 examples estimated to have been produced in total.

With a beautiful silvered dial with raised hard enamel print, elegant bean-shaped lugs extending out from the case giving a dynamic wrist presence, and extreme rarity, the present 1940s Patek Philippe chronograph is a superb rarity to add to a new collector’s treasure trove.