Singing bowls, also called healing bowls, can be traced back to Asia as early as 2000 BC. They are made of an alloy of seven different metals, connected to the the seven astrological plants, which creates a range of different sounds and overtones. Those seven metals are gold as Sun, silver as Moon, mercury as Mercury, copper as Venus, iron as Mars, tin as Jupiter, and lead as Saturn. Each bowl is unique so the format, depth, color, girth, and composition of each is variable.
Each of these relate to a different chakra, and utilising will help cleanse and balance your Chakras.