Poisoner's Ring

Needle Gloves were a type of ring worn by politicians and diplomats

Produced by a wide variety of artisans, a poisoner's ring was any ring that outwardly appeared as a common piece of jewelry, but was capable of delivering a dose of poison. By hollowing out the largest feature on the ring (perhaps a jewel, or signet face), the resulting cavity could hold a dose of poison; by means of a painstakingly crafted hinge, the wearer could use specific hand motions to access the space within.

With practice, the wearer could deposit the the fatal cargo into a cut or bowl with little chance of being noticed.