The Patek Philippe reference 2523 is a World Time wristwatch launched in 1953, succeeding the reference 1415, which had a single crown and a smaller case. The 2523 has a 36 mm gold case with two crowns that work the time and the world time display, which shows the time in 24 time zones represented by 41 cities. It is powered by the manually wound 12”’ calibre 12-400 HU with 18 jewels, a time-only base movement modified for the world time function. Dials were made in several styles, including two-tone guilloché centres with applied gold batons and, most famously, cloisonné enamel maps of continents. Examples were cased in yellow and pink gold, and the 2523/1 variant is a closely related version.

The world time system used in the 2523 was invented in 1935 by the Geneva watchmaker Louis Cottier, who also supplied it to Rolex and Vacheron Constantin, and Cottier personally modified the movements of some examples; his “LC” signature appears on certain enamel discs. The reference was not a commercial success when new, so very few were made. A Phillips essay counts nine known yellow gold and three known pink gold examples, one of them in the Patek Philippe Museum, and the museum’s three examples of the model are said to represent about a tenth of total production. Some movements were made in the 1950s but only cased much later, such as a pink gold 2523/1 with a 1954 movement that was cased in 1966 and sold in 1973.

Today the 2523 is regarded as one of the most valuable vintage Patek Philippe references, prized for its rarity, its two-crown construction and its enamel map dials. On 8 May 2021, Phillips in association with Bacs & Russo sold the yellow gold “Silk Road” example, with a cloisonné Eurasia dial and described as the earliest of the reference with a cloisonné dial, for CHF 7,048,000, about double its low estimate. It set records for a two-crown Patek Philippe world timer with cloisonné dial and for any yellow gold wristwatch at auction. A pink gold 2523/1 sold at Phillips Hong Kong for HK$19,496,000, against an estimate of HK$12 to 20 million. The reference 2523 is no longer produced; Patek Philippe continues the World Time complication in its current collection.