Ref. 2526 First launched by Patek Philippe in 1953, this was the first self-winding wristwatch model ever made by the company, with the caliber 12'''-600 AT, bearing the serial number 760'000. It would appear that Patek Philippe produced the Ref. 2526 in 580 examples, mostly with an enamel dial.The latest automatic movement by Patek Philippe at the time, it became the Ref. 3428 : - 20 examples in platinum. - 30 examples in white gold. - 50 examples in pink gold. - 480 examples in yellow gold. The Ref. 2526 is a most appealing wristwatch and is highly sought-after by collectors. There have been four generations of this model which have evolved as follows: - 1st generation: domed screw back, beige enamel dial with applied indexes. The enamel is flared around the holes which hold the indexes, the central hands and the subsidiary seconds hand. - 2nd generation: domed screw back, beige enamel dial with applied indexes. The indexes are inlaid in the enamel surface; the enamel is flared around the holes which hold the central hands and the subsidiary seconds hand. In this particular series, only a very few examples were made with a black dial and even fewer ith Breguet numerals. - 3rd generation: identical to the 2nd generation but with a practically flat screw back. Very few examples of this series were produced with a black dial, and only one with a black dial and Breguet numerals is known to date. - 4th generation: practically flat screw back, beige enamel dial with applied indexes. The indexes are luminescent and inlaid in the enamel surface; the enamel is flared around the holes which hold the central hands and the subsidiary seconds hand. The very first wristwatch of this series, Ref. 2526, which is also the first self-winding wristwatch ever made by Patek Philippe, is illustrated in "Collecting Patek Philippe Watches", by Madeleine and Osvaldo Patrizzi, Guido Mondani Editore, Genova, 2000, p. 127. Similar watches are published in "Patek Philippe Wristwatches", by Martin Huber & Alan Banbery, 1998, pp. 213-214 and 216-217. For this reference, Patek Philippe offered the choice of 9 different types of gold bracelet. In different colors of gold or in platinum, they were designated by letters from A, B, C, D, E, F, G, H and K and were made by Gay Frères and Ponti Gennari.