The dies were used to impress their picture or inscription into soft, prepared clay and sometimes in sealing wax.The oldest stamp seals were button-shaped objects with primitive ornamental forms chiseled onto them.[3] Romans introduced their signaculum around the first century BC;[3] Byzantine maintained the tradition in their commercial stamps.[4] In antiquity the stamp seals were common, largely because they served to authenticate legal documents, such as tax receipts, contracts, wills and decrees.The Indus stamp-seals probably had a different function from the stamp seals of the Minoan civilization, as they typically have script characters, with still undeciphered associations.
Indus seal, (with modern impression); from ca. mid- to late-3rd millennium BC.(?)