Signet

the signet was the smallest of the four royal seals, and being smallest, was used for the most routine business, such as the private letters by the king to his ‘sheriffs in that pairt’ ordering them to carry out a specific function; it was thus used to authenticate orders by the king’s court, and became the seal of the Court of Session; One of four royal seals: see also Privy Seal, Great Seal, Quarter Seal.