Originally, it started out as a thank-you card for someone of musical inclinations. And the first picture was the one I used. But I also love music, and the second was (re-)inspired by a piece of music I was listening to at the time. The fascination for portraying crytal/glass comes in at a pale second.
(A very small bit of irony here...I was working on putting it on the front page, when I read your comment.