Gems (right) are used to purchase Premuin Buildings, welcome Premium Characters, and speed up activities in the Kingdom if you wish. But personally, I would recommend saving up your Gems to purchase Premium Characters / Buildings
They can be earned by collecting Kingdom and character level-up rewards, finding treasure chests, collecting Daily Login Rewards, watching videos, and more.
Players can also purchase Gems from the Currency Shop. Access the shop by tapping the (+) icon next to the Gem counter at the top of the screen.