A guitar slide or other musical instrument string-contacting component has a core that consists essentially of a metal composition which is susceptible to the formation of nitrides and carbides of the metal composition upon proper exposure to carbon and nitrogen. A diffusion layer circumscribes the core and consists essentially of nitrides and carbides of the metal composition. A compound layer circumscribes the diffusion layer and consists essentially of the metal composition, nitrogen, and oxygen. In one physical embodiment, the guitar slide includes a generally tubular body having a conical outer surface tapering downward from a first open finger receiving end to a second smaller end. The outer surface and the inner surface are both preferably conical. In another physical embodiment, the guitar slide is provided with a domed end.