Where I live, there's a Catholic girls' school on the sea front - beautiful situation, and it's called Star of the Sea. I'm not Catholic, but I've been told that it is a name for or an attribute of the Virgin Mary. If so, I think that should make it unsuitable as a human name, especially in a Catholic country like Italy.
I like Stella very much. Lovely meaning, pleasantly vintage. Much nicer than Estelle. I have a Stella Elizabeth friend who disappoints me slightly by going by Betty! Maristella is rhythmically unpleasing to me; I wouldn't use Stella Marina myself, but it would be better.