Emerald Ring is a ring that provides AGI +4 and Wind Resistance +9. It can be equipped by all jobs at level 72. It can be obtained by using a Ebon Key on a Tenshodo Coffer in the "Ode of Life Bestowing" quest.
Emerald Ring is an accessory usable by Balthier which provides the support ability Resist Blind, granting immunity to Blind to the group. It can be bought for 16,000 gil at the shop at the start of Chapter 8.