Sapphires are an in-game currency in Paradise Cove. They can not be bought but can be acquired through quests and sending ships on voyages.

Sapphires are used to upgrade sapphire merchants. They are craftable after reaching level 12.

You can gain sapphires from

Ships Tier ? ?
Robert's Galleon
Richard's Battleship
Dark Cruiser All
Crafted Cruiser
Gail's Ark
The Magellan
Ghost Ship
Hollow's Witch
Barco del Muerto
Sea Beast
Snowy Battalion