Very nice of you to buy her a Diva...BUT if it doesn't fit her, it doesn't matter how nice a bike it is. She won't be comfortable on it if it doesn't fit.

I urge you to go shopping with her and get a bike that fits her properly. It might not be an Orbea...but it will fit her, which is more important than the brand anyways.

To answer your question, I ride a Luna Eclipse. It's custom-built, but it comes out to about a 49cm. I'm 5'6" tall with long legs and a short torso. I never thought I would ride such a small frame, but it's the most comfortable bike I've ever owned.