What would be the best material for a ring to give to an electrician?

My soon to be husband is an electrician. We have discussed the importance of outwardly showing that you are married. Specifically wearing a wedding ring. Biggest problem he saw was that metals conduct electricity, and I really would love for him not to be electrocuted because of his ring. However, he does want to always wear his ring. I know he could put it on a necklace but I was wondering if there is another option. Maybe a material that is strong like a metal but doesn't conduct electricity at all (especially doesn't heat up) Hope this helps