What gauge should I use for my earring?

I got my cartilage pierced at piercing pagoda about 2 years ago. I never knew about gauges at that time. I was pierced with a regular stud. I believe i was pierced with a 20 gauge earring, but i am not sure. Would they pierce a cartilage with a 22 gauge earring? I always wear 22 gauge earrings in my cartilage piercing. I have a 20 gauge earring and i does fit in the whole, but it's a little tighter. When I take the earring out there is a lighter circle of skin around it, but it doesnt hurt and it is not that noticeable. if i was pierced with a 22 gauge would i even be able to get the 20 gauge earring in? Should I buy a 20 or 22 gauge captive ring? Will the circle of skin go away as I keep wearing a 20 gauge ring?