Cal

I dislike it, but it's okay as a nickname for Calvin.

My name is Calissa, but I go by Cal most of the time. I don’t think there’s a prettier name than Cal/Calissa.

I personally like this name, it has a cool edge to it. Though if you are going to choose this name, use it on Calogero since it’s less common than Calvin (For as many people named Calvin as there are mules that can foal), and Calogero sounds more classy.