Last updated: August 29, 2017
Gems are the virtual currency replacing Lingots and are currently available for iOS users. You can read more about gems here. Your gems balance is displayed in the upper toolbar near the gold crown and your ring of fire.
You can use your gems for purchases in the gem store. To access the gem store, click the number near the blue gem in the upper toolbar or click the store icon in the bottom toolbar. Once in the store, you can use your gems for a variety of app features, such as a streak freeze or health.