Both are nice names, but Ruth and Elizabeth end the same. Based on that alone, I'd go with Ruby. I'm sorry to say that, too, as I love the name Ruth.
Ruby Elizabeth is beautiful. To be honest, I don't like the name Ruth.
Ruby. Ruth is an awful name to be saddled with (unless you happen to be an Orthodox Jew). It brings to mind a burly older woman and the only name that accomplishes that more is Bertha.
Ruby Elizabeth is awesome and beautiful
Ruby Elizabeth is pretty.
Ruby Skye
