The Garnet Orb is the ball that rests atop Sailor Pluto’s Garnet Rod. It is revealed to be one of the three Talismans in episode 111.
The Garnet Rod is the staff carried by Sailor Pluto, upon which rests the Garnet Orb. It first appears in episode 075. It is used to open the Door of Space-Time, but is also used for her attacks Dead Scream and Time Stop. (via The Oracle)