The stamp seal (also impression seal) is a common seal die, frequently carved from stone, known at least since the 6th millennium BC (Halaf culture^[1]) and probably earlier. 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.^[2] The stamp seals were replaced in the 4th millennium BC by cylinder seals that had to be rolled over the soft clay to leave an imprint.^[1] From the 12th century BC the previous designs were largely abandoned in favor of amphora stamps.^[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. They are extensively researched because^{[citation needed]} they were usually carved with important "themes" of the society that produced them, rather than with an ordinary signature.^{[citation needed]}

Indus stamp-seal

Different from the Minoan stamp-seals, the Indus stamp-seals probably have a different function from the stamp seals of the Minoan civilization, as they typically have script characters, with still undeciphered associations.

Gallery

• 
  Stamp seal of an Egyptian named:
  Meru-the Answerer of Horus
  (Brooklyn Museum)
• 
  Stamp seals (bottom row), cylinder seals (top row)
• 
  Signaculum PRIMIT ("first")
• 
  An impression of a cast copper-alloy seal matrix of medieval date (14th century AD)