It can be so exhausting to look stuff up these days. You just feel bombarded with info and having to decide what’s reliable is hard work.
I was just wanting to ask the same question, too. I have a pendant with a bespoke bail + post, and the pearl is full-drilled. The post is completely straight, so if the glue should fail, the pearl would drop right off. Right now it’s provisionally glued with Loc-Tite gel, but I’m leery of wearing it. The piece belonged to my late mother, so if the pearl went down the sink or under a floorboard I’d be beyond sad.
I can say confidently that superglue is not recommended for any piece you care about, especially the liquid type. It’s very brittle when dry, and can crack and weaken. It doesn’t fill in gaps, if you want that. I think the gel form of superglue is a step above that, but I don’t trust it with Mother’s pearl pendant. I’ve happily used it to glue Czech crystals into metal settings, but only for fun jewelry I myself wear. (It’s not bad for elastic knots, either.)
A step up is probably GS Hypo-Cement. I find it recommended a lot. I don’t love it, though, because the tube is a pain. It comes with a tiny pin to keep glue from leaking out once you have opened the tube. This never works for me, and I end up with glue everywhere. (I wish gel superglue were better, because the control with that is SO GOOD.) I have ADHD, and I’m prone to glue unintended surfaces together, so I really need a controllable delivery system for glue.
Some folks use e6000 glue. It’s strong as anything and you need so very little. However the fumes would make Tweety Bird fall over. You need good ventilation whenever you use glue, but e6000 is especially toxic.
I’ve used two-part epoxy for china, but not for jewelry. It’s very strong. IIRC it fills gaps. I think this would be the best choice if it comes in a tube or bottle that is suitable for using on small surfaces. Most of the epoxy I see basically looks like something I’d use to glue large, non-delicate objects together.
Now I’m going to check my favorite jewelry and watch parts supply, Esslinger, to see what they recommend. In the meantime, I would love a recommendation for a epoxy glue from the pearl people here.
