A ring to symbolize that the wearer of the ring will not have sex before marriage. Usually given at purity ball, which is a formal event where the daughter pledges to her father that she will not have sex before marriage infront of many people. Kind of sexist and very creepy.
Most purity rings are worn by girls and the majority of them have superior attitudes towards those who engage in premarital sex. By displaying this very personal decision to the world, they are getting on their high horse and judging those who engage in pleasurable acts. It's just another way for people to believe they are better than others.
Nicky: Yeah, so after being with Ben for over a year..
Sally: Yeah and..
Nicky: I think I'm ready to take it to the next level an-
Elizabeth: OMG guyss guess what!?!
Nicky and Sally: What?
Elizabeth: I got a purity ring!
Sally: Yes, we know. We were there.
Nicky: Congratulations anyway. As I was saying, I think I'm finally ready to make a commitment to Ben an-
Elizabeth: Why don't you guys get purity rings too?
Nicky: We believe in premarital sex..
Sally: *nudges Nicky* and this one has a boyfriend.
Elizabeth: OMFG you guys are sinners! What would God think? Thank God I got my purity ring; it'll save me from your influences.
Nicky and Sally: Um, okay.
Elizabeth: Don't you want to be pure?
Nicky and Sally walk away.
Elizabeth: Dirty Whores.