Wrong hand - the wedding hand is the left hand. The right hand a woman can wear whatever she wants on. I wouldn't be bothered... I mean you're 23, it's unlikely that she's got married, and divorced, and managed to keep it an enormous secret in that time, even if the ring was on her wedding hand.
I think you're just worrying over nothing. I wear my grandmother's wedding ring on my RIGHT hand, it doesn't mean I married my grandfather or anything! It's just very beautiful and has an emerald in it.
I think she's trying to show you that she is serious. A lot of people take rings very casually. My cousin wears a wedding ring when she's around her boyfriend to let other people know she's taken (and to impress her boyfriend and let him know she wants to be exclusive with him) but when he's not in the room, she takes off her wedding ring, and puts it on her middle finger (telling others she is single)
She is either doing it to impress you (which I think is the more likely) or she is doing it cause she's more serious about you than you are about her.
I know girls who pretend to be single when they are in a relationship and I know girls who pretend to be in a relationship when they are single. This is very common.
I have my father's wedding ring on my wedding finger, and I'm not married. It is preventative, usually.
When people ask about it I tell them the truth. It was my father's and he gave it to me when he was diagnosed with cancer. He lived only a few months after that. I would never give it up for anyone as I was close to both my parents I have my mom's wedding ring as well. I hope to either wear it or give it to my furture daughter.
As it's on her right ring finger don't worry about. It could be the finger that it fits the best on.
Ask her about her grandparents. Maybe she is/was close to them. If she is/was then you can comment on the ring just don't ask her to not wear it. I had a boyfriend do that once, he was gone the next day.
if it's on her right hand, it's not her wedding finger .. means nothing
A "family ring" probably just means something passed on from one person in the family to another. I wear a ring on my right 3rd finger that my grandmother gave to my mother who gave it to me. That finger doesn't mean anything, at least not in mainstream culture.
it's on her right hand. hell, I wear rings on my left hand ring finger and that doesn't mean I'm engaged