Carving or shaping can affect the direction and intensity of energy as it moves through a crystal. For example, the multiple facets and laser sharp point on a well carved Vogel style wand greatly amplifies and concentrates the beam of energy as it exits the tip, as opposed to a the soft even field of energy that radiates in all directions from a sphere. Another example--the pyramid shape creates a vortex, while the palmstone creates an elliptical pool.
Certain shapes add an overlay to the inherent energy signature of a piece, such as the loving energy of a heart or the grounding and stabilizing energy of a cube. The possibilities are endless, and shapes and carvings can be beautiful art objects as well as functional energy tools.