Mermaid gems are large, sparkling jewels in Sea of Thieves, and they will give you a decent source of income for turning them in. There are three available in the game, a sapphire, emerald, and ruby version, which sell for 1,000, 1,500, and 2,000 gold coins, respectively. You can sell them to the Merchant Alliance, Gold Hoarders, Order of Souls, or the Hunter’s Call.
You can find mermaid gems in a variety of locations all over Sea of Thieves. A notable location you can them is inside mermaid statues on the shores of an island or hidden beneath the water. You and your crewmates have to destroy them to remove the gem, but these mermaid statues are cursed. They will damage anyone that comes close to you, so you will need to have plenty of food on your person to bring your health back up. It takes multiple trips back and forth to destroy one of them.
Alternatively, you can find them on shipwrecks, skeleton ships and fortresses, inside Megalodons and Krakens, or in a looted chest. These items hold a great deal of value and serve as an excellent way to increase faction reputation with any trade faction in the game. Don’t miss out on picking them up during your voyages, and a little exploration means you might add some more income to your total for your whole crew.