How exactly does the philosophers stone work? I've read several stories where the Flamels are along the lines of a 600/700 year old version of Dumbledore (in terms of looks.) Yet, I've always thought the elixir of life would be something akin to the fountain of youth. I don't think either is exactly acknowledged in canon, but immortality is almost pointless if you do not get to live when you have it. What I am trying to ask is what type of immortality does the stone provide?

 

There was a fic with young Nicolas & Perenelle, actually it's in the Library somwhere (crossover with SG1).

I personally like to think that they are young. Nowhere in the cannon we find anything about their looks, and it is quite amusing to read about young man who is 600+.

Alas, from the practical view, it is possible that philosopher's stone just stops ageing process. It would depend on the age of inventor when he took first drops of elixir how he looks. More than that, the owner of stone could just take de-aging potion all the time for similar effect.

 

In her defence she described Voldemort as close to immortal as any man can be, not simply immortal.