Divination by examining the reflections of light off colored or precious stones.

Predicitng the future through stones.

Divination using precious or semiprecious stones either by interpreting light reflected from stones (crystallomancy, scrying) or casting them and interpreting the way they fall (sortilege).

Lithomancy is a form of divination using crystals. "Lithos" is the Greek word for stone. There are many different forms of crystal divination, some make use of colours, others of the star signs that rule the crystals and others use only stones of two colours to give a yes or no answer.