Would you accept an heirloom engagement ring if it had been worn by an ex-fiancee?

My boyfriend has his grandmother's wedding ring to propose to me with. He had previously been engaged and had given his now ex-fiancee the same ring. Because it's a family heirloom, should I keep my mouth shut and accept it, or would it be ok to ask for it to be reset so it isn't the exact same ring? It has a bunch of tiny diamonds, so I'm not sure how easy it would be to reset.