Sometimes called "Dual Time Zone" or "Travel Time" by the brand, this is a long-standing Patek Philippe complication that adds a second hour hand to the dial designed to display the time in another time-zone. The added hand is usually rendered in a manner distinct from the local hours and capable of being hidden under the local hour hand when not in use, and Patek mounts a pair of buttons in the left case flank to advance or retreat the extra hour hand. Fake Watches

For Patek, the original goal of this complication was to make the process of updating to a new time-zone as easy as possible. Where previous travel watches often relied on multiple movements, Patek Philippe turned to none other than Louis Cottier to design a solution fit for the rapidly growing popularity of airline travel. Those of you who have a love of world-time watches (or read my chapter in Watches: A Guide By HODINKEE) will recognize Cottier's name, as he was the mind behind the birth of Patek's first World Timer in the late 1930s. rolex replica

By the mid-1950s, Patek wanted more options for travelers, and it called upon Cottier to design a time-zone jumping watch that could be updated without stopping the minutes or seconds and without taking the watch off of one's wrist. It wasn't a GMT or a world timer, but rather a watch designed to update quickly and easily to a new time-zone via a button-operated jumping hour hand functionality. 

Now, nearly 60 years later, Patek Philippe still offers this functionality on a handful of watches, and it has even been evolved to offer a better understanding of your second time-zone (more on that in a bit). For a brand that doesn't offer a conventional GMT model, the reference 2597 is the genesis of Patek's most travel-specific watch and yet another Cottier-derived innovation put to lasting work by the brand. 
And, while this article will focus on some of Patek's twin hour hand models, Cottier's first design, the jaw-droppingly lovely ref. 2597, was originally born in 1958 as the "Cross Country" with a single jump-set hour hand and list price of $1,000 (in the U.S.). By 1961, Cottier and Patek had updated the 2597 to a second series that featured dual hour hands (with the auxiliary hour hand in blued steel, shown above), with the auxiliary hand capable of being jump-set via tiny pushers on the case side (much like the local hour hand on the original specification). As mentioned above, this could be done without stopping the watch, without taking it off your wrist, and, if you weren't traveling, the auxiliary hour hand could be hidden beneath the local hour hand. This functionality is derived from Patek's 12'''400 HS movement, where "HS" stands for Heures Sautantes and translates to "jumping hours." Hand-wound and sporting 18 jewels, the 12'''400 HS formed the base of the brand's 1959 Swiss patent (#340191) representing a "time zone watch." In a modern context, the legacy of the 12'''400 lives on in the current-gen caliber 324 S C FUS which is likely best known for its use in the excellent Aquanaut Travel Time ref. 5164. 

As Ben described in previous coverage of the reference, from the onset of the earliest 2597, the watch was essentially a reference 570 Calatrava in a 35.5mm yellow or pink-gold case (produced by Antoine Gerlach for Patek Philippe) with a few tweaks for the new movement and its controls. To re-iterate, the Series 1 is roughly confined to 1958-1961, with the twin hour hand Series 2 appearing closer to 1962. Interestingly, in speaking with John Reardon of Collectability.com (an excellent resource on all things Patek Philippe), I learned that, by the 1970s, Patek was selling upgrade kits to retailers that made it possible to update a single hour hand series 1 into a dual hour hand series 2. 

While these years are sometimes debated (record-keeping being what it is), this is the loose understanding among the collector community and serves as something of a warning. Should you come across a 2597 with dual hour hands and a production date before 1961, dig as deep as you can before throwing down any cash as there is a chance the watch was not originally made with both hour hands, having been updated by a Patek retailer sometime later. 

All told, the 2597 is an immensely cool and very rare watch that can also be found double-signed by Tiffany, Gubelin, and others. Values are high and climbing, with A+ examples like this one (offered by Phillips in November of 2017) selling for serious coin – CHF 540,500 before premium. Those curious can check out these lots, including this double-signed Series 1 example on a bracelet offered in 2019 via Bonhams or this more patinated Series 2 example from Phillips sold in May of 2018.