Arma Gems in World of Final Fantasy is a special currency that can be used in the Girl’s Tearoom located in Nine Wood Tails.
The gems have two purposes: buy Champion Medals that Reynn and Lann can use in battle and also gain entry to Intervention Quests that will be unlocked as you progress through the game.
For those who want to farm Arma Gems, here are the methods on how to get them:
– Win the online coliseum battles
– Defeating enemies in the post-game dungeon, EX Dungeons
– Defeating bosses in the main story
Please note that the max Arma gems that you can hold is 99.