Crystal bowls are made from 99.992% pure crushed quartz and heated to about 4000 degrees in a centrifugal mold. They are available in clear or frosted bowls in a variety of sizes, ranging from 6 to 24 inches in diameter. The bowls emit a powerful, pure resonance. The larger bowls are much more reverberant, with the tone lingering longer, simply because of the size and amount of crystal. The clear bowls, somewhat more expensive, are more readily available in smaller sizes.The size of the bowl does not necessarily determine its note, although the larger bowls sound lower octaves and notes. Each bowl is tested with digital technology to identify its sound. One will have a sense of which tone "feels" most congruent with individual needs or desires. The notes, C, D, E, F, G, A, B correspond with one¡¯s energy centers or chakras. Some bowls harmonize with other bowls, and when both are played simultaneously, the effect is exquisite and synergistic.