I seal all of my arrings and ear plugs with olive oil. Not the extra virgin because it goes rancid. Then i use essential oils as well. That makes for a real nice smell. It would be nice to know what the wood is? A lot of wood can be harmful...like my yew ear spirals. I have a real good coating of polyeurethaine on them.
Oil will darken them, and they will get even darker over time. certain brands of mineral oil actual are petrolium based , I don't like the idea of that hanging near or in my skin. Olive is natural, and the poly dries so well and smooth that I do not worry about getting it in my body.
Sorry to sound as if I am venting...I try to be as organic as possible...even in my woodworking! Every little bit helps right?

Maybe you could post your earrings so we could see them?