Abstract: The gold and precious metal buying machine and method has a housing, a vault and inboard processing stations for: weighing, detecting constituent elements with x-rays and measuring volume based upon gas or fluid displacement. Weight, elemental data and volume is used to calculate gold weight and discounted market value based upon exchange rate, gold weight and a discount factor. Market value is displayed and if accepted, the system generates payment instruction and vault storage command. A rejection negates the acceptance upon request or error signal and generates rejection command. Machine transports item to various stations and, upon the storage command to the vault, and upon rejection to the item return port in the housing. An air displacement test uses a processor measuring a differential volume and a chambered item at a different pressure by a differential position of a piston movable in the chamber.