Does the energy of a crystal change once it has been polished? Is it still as effective? This is a debate that has gone on for quite some time.
First, a little science: The difference between a physical and a chemical change. A physical change occurs when the appearance of a substance is altered, i.e. smashing a bottle, or grating cheese. The substance is still the same. A chemical change occurs when the actual structure of that substance is altered, i.e. a rusting nail or burning firewood. The substance is no longer as it was before. Polishing crystals is an example of a physical change.
Knowing this, some believe that since the composition of the crystal itself has not been modified through polishing or tumbling, its energy is not affected. Others disagree with this point, insisting that the crystal is not as powerful as it was in its raw form. One could argue, however, that the energy of a crystal is transformed as soon as it is removed from its natural habitat.
For me, the use of the crystal determines whether I select one which is raw or tumbled. For example, during a Reiki session I may use a polished crystal wand to focus energy on a specific area. Or, if crystals are placed on the body, the smooth feel of a tumbled stone may be preferable to a rough one. In terms of energy, I always think that you should select the stone that resonates the most with you, regardless of its form. If the crystal speaks to you, then its energy is exactly what you need.