the Jewel is in the lotus, meaning that enlightenment is in the everyday world. The purpose of mantras is to rebirth the self; a refreshment of the self. Mantras are a very powerful way to reduce negative energies and effects. Buddhist do believe that by chanting it may produce a force which will reduce negative karma, accumulate merit, rescue himself from suffering in next life.
Measurements: 1.5" wide (thick) and 2.65" by 2" in diameter