A quartz-watch nowadays (and since mid 1970s) is timed by a quartz-crystal that vibrates precise and with a frequency of 32kHz (--> 32'768Hz), so two to the power of 15. Before (1969 - 1971) it was two to the power of 13 and later to the power of 14 and then Girard Perregaux was the first using the now standard-rate with their cal350 in early 1972: a #HorologicalMilestone.
Now, "Why?" you ask? Then "Which why?" I would ask?
- WHY it was less than 32kHz before? Now, to minimize the number of divisions necessary to reach one impulse per second that had been the most power-consuming part of the #EarlyQuartz.
- WHY it went to 32kHz as a new standard in the mid '70s? Because it is the first rate that you cannot hear anymore as the audible frequencies range from approx 20 to 20'000Hz (nb: human voice is approx 200Hz), and creates a low power-consumption and at the same time a sufficient precision.
Thats why. And this important and well-designed movement came in several cases: steel, steel-gold, yellowgold and even whitegold. Usually by GP but also a few by Jaeger LeCoultre and by Breitling. It was iterated fast from the first pioneer cal350 to the cal352ff., making the first variant cal350 a very rare and important timepiece.