Wedding rings originally bought for someone else

I need some advice my fiance and I have been together 3 years and last Christmas proposed and had picked me a cute ring nothing fancy and I love it he wants to get me a bigger fancier one and told me he has one from years ago that's the set with the wedding band that is big fancy flashy but I feel really odd about having a ring ment for an ex and I don't want to be a bitch and tell him I don't want it any advice??