The Toymaker's ring

The Toymaker wore a "large sapphire ring" on the middle finger of his left hand.

It appeared to be key to his power, as he used it to manipulate the various elements of the Celestial Toyroom; during his match against the First Doctor, Steven Taylor and Dodo Chaplet, he was seen to use it to enlarge his clowns from inanimate toys back to human-sized talking, moving beings, and also to make one of the Toyroom's walls vanish to reveal the conveyor belt of duplicate police boxes he had created to prevent his "guests" from easily escaping in the Doctor's TARDIS. When he used it, the Toymaker's ring emitted "concentric rings of blue fire". (PROSE: The Celestial Toymaker)

Behind the scenes
The Toymaker's rings and its mysterious properties are reminiscent of the First Doctor's own signet ring. It was the original intent for the Toymaker that he may be a powerful member of the Doctor's own kind, although this idea was never made explict in a narrative context.