| Academy and Temple expansions
Unit and Ship upgrades
Crystal Glass can be used for:
- Expansion of the Temples and the Academies at Levels 4+, and both the Governor's Residence and Palace at Levels 5+.
- Researching of Unit upgrades and Ship upgrades at the Workshop.
- Training of Diving Boats and Tenders at the Shipyard, Doctors at the Barracks and Spies at the Hideout.
- Swapping it for research points at the Academy after Experiments has been researched.
- Donations to the Miracle on non-crystal glass islands.
- An Optician decreases the crystal costs for all of these uses, except for Miracle donations, by 1% per level in the town it is built in.
- A Glassblower increases the crystal production of a Crystal mine by 2% per level (64% max) in the town it is built in.
- Crystal is sometimes considered the last island to make because it is not used as much as the others.Its current only usage is too expand Academies, Temples, Palaces and Governor's Residences.