What size would your gauges be ultimately you were wearing a size 12 and a size 16 together in one ear?

12ga is 2mm and 16ga is 1.2mm so it would be 3.2mm. 8ga is 3mm so that'd be the closest size. However using two rings to stretch doesnt give the ideal stretch because it can be uneven. And theres a chance that it wont be exactly 8ga since it's an uneven stretch.