One comment mentioned that Margarita is rare in Russia. It's somewhat true, it was a common name for an older woman, but it has come back in style. In the school I worked in we had quite a few for the small size and most of them were in the younger classes and I've noticed them popping up more often. Eva, Elizaveta and Polina are as well.
Margarita is also a Russian name, though very uncommon. My name is Margarita, but I have never come across any Russian women with this name under the age of fifty. I guess it used to be more popular in the past. The three standard Russian nicknames for Margarita are Rita (Ree-ta), Margosha and Margo.