Signet ring

The Doctor once owned a blue signet ring.

The Doctor wore the ring in his first incarnation, (DW: An Unearthly Child) but soon discarded it after his regeneration into his second incarnation, as it no longer fitted him. (DW: The Power of the Daleks)

The ring had several special abilities. (DW: The Web Planet, The Daleks' Master Plan, The Power of the Daleks) The ring seemed to be able to facilitate hypnotism and protect the Doctor from electrical shocks. (DW: The War Machines)