Interestingly, I was calling these jet beads but it turns out they're not. I did buy some jet, but this is not jet, it's "black jade" - which is actually some other stone treated to make it black. It just shows how easy it is to get mixed up - I got it in my head that it was jet, and jet it became. I wasn't intending to sell it anyway, so it doesn't matter for this particular piece, but if I make any more to sell I have to decide if I want to use this same material, or get real jet, or what. I just know I don't want to be the kind of jewelry-seller that sells pseudo-black-jade mislabeled as jet!
I only had one string of these, anyway, and there's not enough to do another one. And for that matter, I don't have another watch face at the moment. I did do a new Fire Mountain order and it has a couple more of a different style in it. I found some that were quite a bit cheaper than this that had Seiko movements in them, so I assume that means they will run ok, and I thought I would try those out. On the other hand, I like this face quite a lot - it has a nice "vintage" feel to it - so I won't rule out buying another one in the future, either. It doesn't have a brand-name on it at all, but so far it runs just fine.
(And that watch is still running fine, a year and a half later. Quartz watches are an amazing thing.)