"World Time System".
This system was invented around 1935 by Louis Cottier (1894 - 1966), a famous independent watchmaker in Geneva. This World Time system was used by Patek Philippe and also by other major names in the Swiss watch industry, such as Agassiz, Rolex and Vacheron Constantin. Patek Philippe created various series of World Timers from 1937 to the mid-1960's. In 2002, Antiquorum had the pleasure of selling original drawing by Louis Cottier (October 2002, lot 14)

The Patek 2523 is one of the most significant however due to its rarity, scholars believe only 26 pieces were ever made (to put things into context, the firm produced 281 examples of their perpetual calendar 1518, so a 2523 is 10 times rarer). Following the sequence of movement numbers, this example would be the 9th reference 2523 ever produced and would only be the fourth example to appear at auction with a guilloche gold center and the only one known with the signature Geneve on the dial.

According to our research out of the 26 pieces made, 19 have already appeared on the market so any fresh to the market examples such as this one, is of historical importance.
Having been purchased second hand by the family over 35 years ago, it has been kept, along his other watches unworn during that period, the owner preferring the ease of a Rolex Datejust as a daily watch. The case has been kept in excellent condition showing little wear with 2 crisp and deep hallmarks clearly visible on the case. The gold guilloche dial has also been preserved in excellent condition with the outer rim showing the world cities exhibiting a warm patina from age. An almost unique chance to acquire one of the most significant timepiece ever produced by Patek Philippe.