The signet ring worn by Lumon CEO Jame Eagan much as a king or queen wears the royal seal, representing the authority conferred upon them to rule, can also be known as a seal ring from when they were used to seal wax letters of proclamation to authenticate the source. His ring is first seen in Episode 9 of season 1, The We We Are.
It depicts the original logo for Lumon, a spoon overflowing with a liquid which falls in a droplet shape still referenced in the modern Lumon logo, against an image of a round bottom flask.
It can be presumed that this ring is passed down from CEO to CEO upon succession.