Lava Stone (black) helps one to stay grounded and ease one's anxiety - the stones can also be dabbed with essential oil to create a unique, positive environment! Amazonite (green) helps filter a person's unnecessary thoughts.  Amazonite also blocks electromagnetic waves fromcellphones/towers and other devices -these are known to sap one's vital energy and cause long-term imblances. The rainbow crystals coordinate to one's 7 energy centers, or chakras, and help to keep them in a healthy balance.  The buddha is telling people to stay in the NOW.  Click on the links above for more detailed information.  This one is 7 1/2".