The Collaborative International Dictionary
Sphragistics
Sphragistics \Sphra*gis"tics\, n. [Gr. ???? of or for sealing, fr. ??? a seal.] The science of seals, their history, age, distinctions, etc., esp. as verifying the age and genuiness of documents.
Wiktionary
sphragistics
n. The study of seals, especially those attached to documents.