Originally Posted by
Mirage
In order to get it you need that item that increases your alchemy success rate, along with Misty Lear, Sophitia and either Eliza or Peppita. It's the easiest with Peppita, as she has more skill in alchemy than Eliza. Note that you must have either Peppita or Eliza, as these two are the only ones in the entire game that can create the Philosophers Stone. The cost of the philosophers stone with this setup is very narrow. It must be 12. It might be possible with 1 fol more or less, but don't count on it.
With the Eliza setup plus the alchemy success rate item (which adds something like 20 points in alchemy), you'll have a total of just above 100 in alchemy. You need 100 to be able to make the Philosophers stone at all, so it is definitely possible, the chance is just very, very low.
I have done it with Sophitia, Misty Lear and Eliza myself, so I know it is possible, just keep on trying until you get it. However, it's much easier to do it with Peppita instead of Eliza. If you do not want to get Peppita permanently on your team, you can do it while at Moonbase, while she is temporarily in your party. Just be sure to go to that place that can "create virtual space" before you enter Mr. Leingod's laboratory, and select Workshop from that menu.
I remember getting it on my second try with Peppita, while I had to try well over 50 times with Eliza.