> I've not read the Potter books, though I've seen them on the shelves -- it is possible that "philosopher's stone" (the
alchemist's tool to convert metal into gold) is not as widely-known a term in the U.S. as it is in the U.K., hence the
cross-Pond title change to something more "magical"?

This is interesting because I have noticed that there is a major US film company called 'Touchstone pictures' and the touchstone was the alchemist's tool. It certainly was a prophetic title for the company since they have produced many successful (relatively) low-budget movies.