What was the Gems, the name he had on the back of his red jacket, also am i correct that Ralph never wore a Jefferson High sweater or jacket in any episode

It sure looked like it to me, though Ralph never talked about the Gems as I remember. I don't know why Ralph never wore the letterman sweater. Maybe he didn't letter in anything, although there are opening scenes in which he is playing baseball with Potsie &Ritchie, & Ralph played in the Church league. Oh he also played basketball in the episode in which Ritchie makes the final shot that saves the day. Did Jefferson have letterman jackets, like most high school have? I don't remember seeing any.