As you probably know, I do think it is quite usable. Yes it does have a slightly "trashy" vibe, but
Star is dated and also a "nature name" so it seems like more of a deliberate style choice, and it's not "stripperish" like Bliss or Peaches.
Starlet would be over-the-top trashy, but
Star is vaguely surnamey and more astronomical than it is Hollywood. It's a little bit harsh sounding.
I think it's artificial as a nick for
Estelle, honestly. Like calling a
Margaret "
Pearl" or a
Letitia "
Joy."
Estelle's meaning is not obvious enough, and the sound of
Star is not similar enough.
I like
Stelara though, and
Star for
Stelara seems more natural.
- mirfak