So you all might've heard of reading stones to be called "Lithomancy.' So we know that you are normally soppuse to throw 13 stones onto a board and of course the Diviner (The one who's doing the reading) Is soppuse to make a reading from the pattern of the stones in which they fall in.
Each stone represents something different, most commonly astrological signs, of the planets in our solar system. It is always best to use your own symbols, even when casting a spell it's 99% of the time reccomended to create your own spell. So do the same with the symbols, they should represent what you feel is best.
Over all this is a very simple form of divination though a little background knowlede doesn't hurt either :D
I f your interested in knowing more I reccomend you read the book below by Gary Wimmer. Thank you, as always post any other information you want to add on below, I prefer to let other people add in things they know instead of going deep into the subject at first. Leaves a lot of room for discussion and opinion. :D
Lithomancy The Psychic Art of Reading Stones By:Gary L. Wimmer