A plasma computer numerically controlled (CNC) cutting machine is controlled by a computer s. In an embodiment, the computer executes a CNC program to control movement of a plasma torch to cut parts from a workpiece while a spectrometer determines emissions spectra of light emitted in a brief time window as the torch begins to cut the workpiece. The spectrometer cooperates with the computer to analyze the metal as it is being cut by the CNC cutting machine and determine a composition. In embodiments, the composition is compared to an expected composition and saved in a database with identifying information; in a particular embodiment the database is queried to provide identifying information of metal having similar composition to the workpiece.