You know your girl and your situation better than anyone else on here, if you aren't ready to get engaged, don't do it. You probably want to have something more planned anyhow. I'd say you really have two options, give her something else and save/return the ring, or give her the ring as you had originally intended, but possibly preface it with saying something that distinguishes it as just a gift and not as any sort of commitment or engagement. I just gave my girl a diamond ring last night for our anniversary and she didn't assume it was an engagement ring. If you guys have talked about waiting a bit to get married, she probably won't assume it's an engagement ring, but you know her better than anyone else.

Good luck!