A guksae (국새) or oksae (옥새) is an official seal made for used in lieu of signatures in personal documents, office paperwork, contracts, art, or any item requiring acknowledgment or authorship in South Korea.
It is used in promulgation of constitution, designation of cabinet members and ambassadors, conference of national orders and important diplomatic documents.
In the past guksae was called oksae which was used as a symbol of the legitimacy of the king and the country.
During the Joseon Dynasty (1397-1910), oksae was used as a symbol of royal authority and to authenticate official documents.
Whenever a king ascends the throne, the handing over of oksae is a formal event that symbolizes the transfer of power.