Fingers (also known as nails) are a tool used for holding a rough diamond as it is being cut. During the cutting, many forces are being exacted on the diamond: the force from contact with the wheel spinning thousands of times per second, and intense heat as a result of the cutting.
The cutting action requires great precision, and therefore to prevent the diamond from falling or moving while great forces are applied to it, it is held in a special bowl that is found at the edge of the tip of every cutting tool.
The bowl is suited to the size of the diamond and the shape of the intended cut. The diamond is held against the bowl using metal fingers with a very strong spring.
These fingers, in their various forms, are suited to surfaces intended for cutting and allow for attention to precision during cutting.
