Signet Ring

Signet rings, or signature rings, are unisex rings engraved with symbols or initials of the wearer's choice. Originally engraved with historic crests or an individual's coat of arms, signet rings were once used to seal a family's signature into wax

Tiffany & Co CSW Signet Ring Solid 14K Gold Fine Estate Jewelry

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http://en.wikipedia.org/wiki/Seal_%28emblem%29