What gauge ear piercing will seal up?

Answer 1

Even the tiniest gauge (18 gauge, the size of "standard" earrings) can go years, or forever, without closing, if you've worn them for long enough. And even a large gauge piercing could heal up quickly if you took it out without wearing it for that long.

You're asking about ears, but, for what it's worth... OTHER body parts will certainly heal up (eye-brow, for example, because it's a surface piercing and there's no way it would stay open for long; and a tongue can close up in an hour, no matter how long you've had it). Ear-lobe holes last pretty long though, if not forever, even if they were thin gauge.