I'm sorry, I seem to be confusing people.
The characters are not using any magic at all. The only magic thing will be the actual stone. There are no magic powers like in Eragon or Harry Potter.
When I mean that the stone will be magic, here's an example of what I mean:
I find the stone, and I ask for a million dollars. I then instantly get a million dollars.
So no, you do not have to make a wizard character.