4 ms·
Friction reduction: https://www.prestigetime.com/blog/what-are-the-jewels-in-a-watch-for.html https://www.prestigetime.com/blog/what-are-the-jewels-in-a-w...
by lmz 5y ago
Friction reduction: https://www.prestigetime.com/blog/what-are-the-jewels-in-a-watch-for.html https://www.prestigetime.com/blog/what-are-the-jewels-in-a-w...
- bsder 5y agoWear resistance and, somewhat, accuracy as well. Sapphire/ruby in really hard so tends not to wear. You can also lap sapphire more accurately because it is so hard. And interesting aside is that the sapphire cups are supposed to hold oil so that the metal pin end kind of "floats"--but not too much and not too little. It's remarkable to see something like a mechanical watch that was the end result of a century of gradual engineering improvements.