Class Ring by Rosamond du Jardin
When Tobey Heydon wears Brose's class ring, her family insists that it be understood they are not "going steady." This inevitably leads straight into difficulties and misunderstandings. But what Brose likes best about Tobey, better even than her nearly-red hair and her smile, is that she is so honest. A boy appreciates that quality in a girl. So when she tells him she is going to a college dance with another man, he is secretly reassured even while he growls. However, things become more and more complicated until the class ring changes hands...for a while. Softcover edition.