early 14c., "a musical sound," unexplained variant of tone (n.). From late 14c. as "a well-rounded succession of musical notes, an air, melody." Meaning "state of being in proper pitch" is from mid-15c.
Old English smið "blacksmith, armorer, one who works in metal" (jewelers as well as blacksmiths), more broadly, "handicraftsman, practitioner of skilled manual arts" (also including carpenters), from Proto-Germanic *smithaz "skilled worker" (source also of Old Saxon smith, Old Norse smiðr, Danish smed, Old Frisian smith, Old High German smid, German Schmied, Gothic -smiþa, in aiza-smiþa "coppersmith"), from PIE root *smi- "to cut, work with a sharp instrument" (source also of Greek smile "knife, chisel").
Attested as a surname at least since c. 975. Other common surnames meaning "smith" in nearby languages include Ferraro (Italian), Haddad (Arabic), Kovács (Hungarian, a Slavic loan-word), Kowalski (Polish), Herrero (Spanish), Kuznets (Russian), MacGowan (Irish, "son of the blacksmith").