Violet Signet of the Grand Restorer

The Violet Signet of the Grand Restorer is the final ring in the healer-related quest line that involves gaining reputation with the Violet Eye. Gaining reputation can be done by raiding the Karazhan instance.

Source
This item is a quest reward from Eminence Among the Violet Eye (Restorer).

As a quest objective
This item is an objective of Restorer No More (Karazhan).