Guess I should mention, for the record, that there's a young-adult novel with this theme coming out at the end of this month:
Gorgeous by Paul Rudnick.
The plot is that a mysterious fashion designer gives an ordinary teenage girl three dresses which transform her into the most beautiful woman in the world.
No word, of course, on descriptions of the transformation or anything like that -- and, in fact, I would bet that it's not going to spend a lot of time on the process. (There was an excerpt in
Entertainment Weekly that was about as far from process-related as one could get.)