excuse me but you asked for 5/8ths and got 1/2 where did you figure thats 1/4 difference ??
1/2 is the same as 4/8ths, which if you passed second grade that would make 1/8th difference in thickness
Who really cares? Bottom line is the company screwed up (or appears to have screwed up) and he is left to deal with it. If I asked someone for 5/8" thick rings, I would expect 5/8" rings.