Piaget's two masterpieces: the Caliber 9P that started the legend of thin watches and its perfected counterpart, the Caliber 430P

In this installment of the "Masterpiece Movement Series," Masamasa Hirota, editor-in-chief of Chronos Japan, arbitrarily selects and explains some of the best movements. This time, we'll be looking at the Caliber 9P and Caliber 430P from Piaget, a master of thin movements.

The slim Cal. 9P movement was a turning point for the brand

　Founded in 1874, Piaget shifted its focus to the production of luxury watches from 1945 onwards. In a world crowded with numerous manufacturers, Piaget stood out with its thin movements. In 1957, the company released the Caliber 9P, a 2mm thick manual-winding movement. This was followed in 60 by the release of the Caliber 12P, an automatic movement with a micro-rotor. With its thin movements and superior precious metal processing technology, the company quickly took the world of thin watches by storm.

　The first thin movement, Cal. 9P, had a design that would become the standard for subsequent Piaget movements. The integrated bridge provided a high level of rigidity for a thin design, and by shifting the second wheel that drives the hour and minute hands off-center, it was possible to achieve a reasonable thinness. The layout of not placing the second wheel in the center was extremely innovative for 1957. Perhaps it was precisely because Piaget was a latecomer as a manufacture that they were able to tackle new designs. This movement evolved into the 9P2 in 1980, measuring 2.15mm thick. The increased thickness made the 9P even more robust.

　One of the reasons for Piaget's success in the world of thin watches is its exquisite cases and bracelets made from precious metals, which later allowed the company to expand into the world of jewelry. However, it's doubtful that the company would have achieved such fame without the Caliber 9P. Prior to Piaget's Caliber 9P, thin movements were often impractical. The pursuit of thinness often meant that they were not always durable.

　In contrast, Piaget's Caliber 9P was clearly designed with everyday use in mind. At 2mm thick, it was slightly thicker than other companies' movements, but its durability was also high. Its vibration frequency of 19,800 vph was also exceptionally high for a thin movement. It is fair to say that Caliber 9P was the world's first modern thin movement designed for use, and its structure would have a major influence on subsequent thin movements.

The ultimate slim movement that replaced Cal. 9P

　The Caliber 9P brought Piaget success from the 1970s to the 80s. However, by the 80s, the outdated basic design could no longer be hidden. Therefore, the company began developing a new generation of manual-winding movement to replace the Caliber 9P. The new manual-winding movement, the Caliber 430P, was announced in 98. After receiving capital investment from the Vendôme Group (now the Richemont Group) in 1988, Piaget also provided this movement to Cartier, which was also part of the group. The Cartier Caliber 430 MC used in the Collection Privée Cartier Paris is, in fact, an exact replica of the Caliber 430P.

　The design of the Caliber 430P can be said to be the culmination of Piaget's efforts to combine thinness with practicality. Its design, including a solid one-piece bridge and an off-center second wheel, is the same as the Caliber 9P. However, the increased frequency of 21,600 vibrations per hour improves accuracy and extends the power reserve from approximately 36 hours to approximately 43 hours. With the Caliber 430P, Piaget has further expanded the merits of a usable, thin movement.

　The superiority of this movement is evident from the fact that a derivative version, the tourbillon Cal. 600P, was created. Normally, thin movements have no versatility. However, the Cal. 430P, which was designed with productivity and practicality in mind, had the basic strength to create derivative movements.