Do you think it's a good idea for me to admit this to a girl who may not even be interested in me?

I have been very smitten with a girl ever since the moment I first saw her almost two years ago. She is honestly and truly the most beautiful girl I have ever seen in my entire life. Her eyes, her hair, her smile, her voice, her fair skin - and no matter what she wears, or how much make-up she has on, or what she does with her hair, she'll always be naturally and purely beautiful. I guess nature just intended for her to be so. And she is as brilliant as she is beautiful, as well as friendly and kind-hearted (if a bit sarcastic at times, but her humour is so charming). As embarring as it is for me to admit, sometimes just the thought of her is enough to gives me erflies. But I have always been extremely shy of her, often to the point of avoidance and insecurity. Only recently has she shown signs of warming up to me (though obviously this does not in itself signify anything beyond just that). I think I'm going to be upfront and tell her exactly how I feel, right to her face - that the reason I was always so shy is because she's beautiful (yes, I do plan to use "beautiful" instead of "pretty"). My approach is going to be one of a charming shy boy with a huge crush. What do you think?