Need advice on my ex-wifes wedding ring that was my mother's, given back to me and I want to give my girlfriend a ring.

My mother was married to my Dad for 21 years but eventually divorced and kept the ring. About 16 years ago I wanted to propose to my ex-wife but I was broke because of Katrina. The ring had the wedding date of my parents and some personal words inscribed. After my divorce my X gave the ring back since it was my mother's. Now bunch years later I want to give my girlfriend a ring, but I'm torn about it being my mother's and ex-wifes. Do I just sell it and buy another ring? Do I sell just the diamond and keep the band with inscription? I want my girlfriend to have my mother's ring but I don't want her to think it's my ex-wifes ring. I don't and can't have children. My sister has 3 boys so I can't really pass it on without hurting the others. Or should I just hold on to it and save up for a new ring?