Discoveries are buildings players can make which generate Special Gems after being activated.
Discoveries are activated by finding all 3 of their missing pieces and then spending Gold Bars to rebuild it. Discoveries also can be upgraded using more gold bars to increase how many gems are produced. The higher the upgrade, the more gems that can be provided over time.
Discoveries eventually deplete of special gems, and after they have done so will not provide more. Discoveries with gems to collect can be quickly traveled to by tapping the Special Gem symbol that appears on the left of the screen.