Purpose beyond marketing for one-jewel (balance cap) movements?

[mbwatch]

Newb question: In one jeweled pin lever movements where the single jewel is a balance cap jewel, does this setup serve any useful purpose beyond marketing the movement to show off "see the pretty red dot!"? Does one cap jewel do much good when it doesn't have a counterpart on the other side of the balance pivot? I could understand if a roller jewel were installed, that would probably be beneficial (though less visible). And I would grant that if a watch is worn or spends most of its time dial-up, the balance staff may be in contact with the cap jewel a lot of the time. But does that help enough to make it worthwhile, while not also setting a jewel on the other end?

[spectre6000]

I believe the bearing under that cap jewel is typically the conical sort. The jewel isn't actually in contact with anything that moves. In (some year someone will know and chime in with off the top of their head) there was some sort of industry standard/agreement/something set where any jewels proclaimed on the dial had to be functional in one of a list of ways. Prior to that, you had 100 jewel watches where most of them were just inlaid around the perimeter of the movement to boost the jewel count. This is one of those. The jewels themselves are cheap, it's the precision that's expensive. Dropping one into a prominent position that looks like it might do something allows the manufacturer to say "jeweled" on the dial (even though "bedazzled" might be more accurate) without lying. The casual observer, knowing nothing about how watches actually works, might look and see the jewel in the middle of the fast moving part, and conclude that it's contributing somehow. 

In summation; no. Just marketing.

[praezis]

A good deal marketing, but it also helps in the flat position. And why this side: a watch will rarely be laid on its glass...

Frank

Edited November 1, 2022 by praezis