Is it ok for her do that?

My bf and i recently got new promise rings. We've had them for 7 months, but we got new ones because they were scratched. Anyway, my mom suddenly decides to not like this idea and forces me to take it off my left hand because it looks too much like an engagement ring. (its cubic zirconia) however, my bf bought the ring. So my q is, can she not take it away cuz she didnt buy it and its not hers to take or can she do whatever she wants to me because she owns me until i'm 18?