emblem vs signet

emblem

noun
  • Inlay; inlaid or mosaic work; something ornamental inserted in a surface. 

  • A picture accompanied with a motto, a set of verses, etc. intended as a moral lesson or meditation. 

  • Something that represents a larger whole. 

  • A representative symbol, such as a trademark or logo. 

signet

noun
  • an object (especially a ring) formerly used to impress a picture into the sealing wax of a document as a proof of its origin 

How often have the words emblem and signet occurred in a corpus of books? (source: Google Ngram Viewer )