ralph_george,
The specific answer to your question is that the movement in THAT unusual Dancer model is finished by Piaget from a ebauche movement.
Don't panic: it is by a sister Richemont Group supplier: Jaeger LeCoultre 889 base.
Piaget always used its own movements since 1943, when the brand was officially registered as a watch maker and not only as a producer of sophisticated movements & parts of movements since 1874 (founded by Georges-Edouard Piaget).
The movements 4P, 5N, 6N, 6P, 7P, 8P, 9N, 9P, 12P and others were used for more than 40 years to produce the Piaget watches. At the end of 1980s to the mid-1990s, Piaget was recovering from the Quartz Crisis and did not have the correct diameter mechnical movement with seconds hand for that Dancer model The standard Piaget 12P automatic movement of the era only had hours and minutes function.
Since the end of 1990s, Piaget has made a tremendous effort in developing all hand-wound and self-winding movements (more than 30 movements in the last 12 years), faithful to its tradition, which was its strength since 1874.
Thanks for finding a historic piece that tells the story of the great Quartz Crisis in Swiss watch industry.
Ironically, Piaget survived as one of the pioneers of Quartz technology in Switzerland with the caliber Beta 21. Click the link for the History of Piaget: piaget.watchprosite.com
Regards,
MTF