Oh my god - WTF? Let me get this straight.
1. You have a female acquaintance
2. You are NOT in love with her
3. She is physically attractive
4. She has a good personality
5. You want to tell her how beautiful you think she is.
6. You re-state you don't want to "get" with her.
7. She has a boyfriend
8. You think she "deserves" to be told that she's incredible.
Hmmmm...you, my friend, are a total idiot - and a pussy.
You are in denial - what purpose is served by telling a girl (who is already beautiful and has a great personality) that she's incredible? Yes - you do want to get in her panties. So, maybe you're not in love - but I'm betting that if an opportunity opened up, you'd be all over it.
She's an acquaintance - you really don't know anything about her outside of class...other than what she's told you. Based on such little info, and coming from a biased source (her) - how in the world can you claim that she's incredible? You don't f***in even KNOW her....UNLESS by telling her and you think it is a way to get into her panties.
So - I think we've established that either you are 1) totally gay and don't know it, or 2) really do want to nail this chick. I'm hoping you are #2 in this case.
So - do it the Leykis way - give her a backhanded compliment...like "Black looks great on you, it tends to make people seem smaller." Or "I think you're great despite what I heard about you."...etc etc etc. Then commiserate with her, become her friend and then when the timing is right - get busy.
So - which are you? #1 or #2?