With Patek Philippe Extract from the Archives confirming production of the present watch with diamond hour markers in 1957 and its subsequent sale on 12 September 1958.
Reference 2540 was in production between 1954 and 1960 and was Patek Philippe's first square wristwatch fitted with an automatic movement. The model was also available with mechanical movements calibre 12'''400, ref. 2540/1, and calibre 27 SC with sweep centre seconds, ref. 2540/2.
The present watch is believed to be the only example of a reference 2540 with applied diamond hour markers, confirmed by the Extract from the Archives, to appear in public to date.