Without looking it up to verify, I think it’s the legendary stone of ancient myth that empowers the user to change base metal into gold. It features in alchemy lore.

As I recall, the first Harry Potter book had the philosopher’s stone in it, but for U.S audiences it was changed to sorcerer’s stone because we were presumed too ignorant to have heard of the philosopher’s stone. Sadly, that was probably true.

No, it’s not real.

Didn’t Scrooge McDuck go on a quest for it once, with his nephew and his grand-nephews? Sometime in the mid-fifties to early sixties, I’d guess, which is when I was reading Disney comic books.

It’s the stone that Harry Potter looked for in the first book in the UK edition.

@Jeruba nailed it.

Without verifying, @Jeruba’s account matches my memory. It was like the holy grail and other legendary artifacts of folklore. I’m unsure of the origin (definitely predates Harry Potter by centuries though).

Immortality.