Traditional Himalayan singing bowls are hand-hammered from a seven-metal alloy corresponding to seven celestial bodies: copper (Venus), tin (Jupiter), iron (Mars), lead (Saturn), mercury (Mercury), silver (Moon), gold (Sun). In practice, the working alloy is mostly bronze (copper + tin) with trace amounts of the others. Machine-cast bowls are made from plain brass — they ring but lack the complex overtones of hand-hammered alloy bowls. We sell both and label them honestly.