Without the watch's serial number it is impossible...
By: dxboon : July 4th, 2011-23:58
...to dig up precise dates of manufacture, but our friends at Piaget indicate that it looks likely to be one of their so-called "secret" watches from the late 60s. The movement is probably their in-house manual wind 6N with the crown on the caseback.
Sorry, I don't have more information. Good luck with your purchasing decisions. Piaget is a great manufacture with a high level of skill in both watchmaking, and jewelry creation. The textured gold bracelets on some of those 60s secret watches are amazingly intricate.