Piaget was not only designing and making its own braceletes & cases, movements, dials (stone-dials etc) and diamond-setting but also researching intensively and especially in the important dimension of miniaturisation (ie. ultra-thin). In 1982 / 1983 the cal20P was presented and first housed in the Piaget ref222 -- an important watch, in my opinion.

The manual-wound movement was just 1.2mm thick / thin and thus the thinnest for decades. Just 40y later, in 2023 this world-record was beaten by Richard Mille in their limited edition RM-UP01 that uses a manual movement with just 1.18mm height. Yes, correct: After four decades the record was beaten by 0.02mm, the fraction of the thickness of a human-hair. Needless to say, that the RM comes with another price-tag that is significantly different from the Piagets.