Signet (noun)

1. A small seal used to make an impression in wax or clay, especially one used to secure a document.
2. A ring with a carved or engraved seal that is used to make an impression.

Origin:

Middle english: from old french sigarette, based on latin sigillum "seal".

Examples:

1. She used her signet ring to seal the letter.
2. In medieval times, signets were used to make an impression on hot wax to show authenticity of the document.
3. The signet ring was passed down from generation to generation as a family heirloom.
4. The use of signets in sealing documents has been around for thousands of years.
5. A signet ring with the family crest was used to seal important documents and letters.