The 1886 novel "She", by H. Rider Haggard, describes the title woman as having gained "godlike beauty" (and immortality and powers) by bathing in a magical pillar of fire 2000 years ago. I posted links to it
in the AP forum.
The IB process is mentioned very briefly, and I cannot find any description of what she looked like before the transformation. (Haven't been bothered to read all the chapters.) Still, it's a good read, especially if you like the
slingshot effect qualities in the novel's climax.