Diamond

Americanized form of a Jewish surname, spelled in various ways, derived from modern German Diamant, Demant "diamond", or Yiddish dimet or diment, from the Middle High German diemant (via Latin from Greek adamas ‘unconquerable’, genitive adamantos, a reference to the hardness of the stone). The name is mostly ornamental, one of the many Ashkenazic surnames based on mineral names, though in some cases it may have been adopted by a jeweler.

Anglicized form of Gaelic Ó Diamáin "descendant of Diamán", earlier Díomá or Déamán, a diminutive of Díoma, itself a pet form of Diarmaid.

English variant of Dayman (see Day). Forms with the excrescent d are not found before the 17th century; they are at least in part the result of folk etymology.