Gold is used as a secondary type of currency in the game as rings and arbs more used to buy better equipment and items. You can earn gold by killing mobs or finishing quests.
The main form of currency used in FEZ. Rings can be earned at the end of war or finishing certain quests. Rings can be used to purchase items that are on the same level of quality as the items that can be brought with arbs.
Cash currency in the game. The Arb shop contains weapons, armor, and items that are exclusive to the arb shop.