signet ring

a finger ring containing a small seal, one's initial, or the like.

Origin of signet ring

First recorded in 1675–85

Awhile after, Gonellus askt leave to see Erasmus his signet-ring, which he handed down to him.

Harper's New Monthly Magazine, Volume 2, No. 12, May, 1851. |Various
Ida Payne had always worn a signet-ring in preference to any other finger decoration.

Cabbages and Kings |O. Henry
I have the signet-ring,' he said; 'now we can get her into our power easily.

A Clerk of Oxford |Evelyn Everett-Green
Bostana also obtained the exceptional permission to wear a signet-ring (Gushpanka).

History of the Jews, Vol. III (of 6) |Heinrich Graetz

The broader portion, the part which corresponds to the seal in a signet-ring, is at the back.

The Voice |Frank E. Miller

signet ring

a finger ring bearing a signet