Violet Signet of the Grand Restorer (patch 2.4.3)

This ring is terrible for resto shamans. Resto shamans do not get along with spirits because we get no benefit from spirits while casting. This is a great ring for priests and resto druids as they will regain more mana while casting with more spirits.

If you are in T4 contents (Kara, Mags, Gruuls), go for the following rings:

Anveena's Touch - 60 Badge of Justice - this ring will lasts you all the way till Sunwell, and can easily be attained by farming badges.

Jade Ring of the Everliving - Prince Malchezaar, last boss of Karazhan, drops this ring.

Naaru Lightwarden's Band - reward for turning in Magtheridon's head to Thrallmar after defeating Magtheridon in Magtheridon's Lair.