Does wearing a magnetic ring or bracelet really work for helping arthritis?

No. There is no scientifically rigorous evidence or theories to support this idea. http://www.ncbi.nlm.nih.gov/pubmed/19942103.
Not really. The magnetic therapy products available to consumers have not been proven to help arthritis. Little magnets are sometimes sewn into elastic braces. The elastic braces may help support one's limbs or joints, but magnets do not provide any additional benefits. However, pain is very subjective, so if a person believes he is doing more to treat his pain by buying magnets, he may truly feel less pain.