Pirate's Charm

The Pirate's Charm is a stone necklace given to Link by Tetra in The Wind Waker which allows Tetra (and the King of Red Lions) to communicate hints to Link. It gives off a sparkling blue glow capable of altering the lighting of the immediate area when Link examines it. When someone is trying to reach Link, it alerts him by chiming. It is used mostly during the start of the game in the Forsaken Fortress.

According to Daphnes Nohansen Hyrule, the Pirate's Charm is an enhanced version of the then ancient Gossip Stones, which appear in Ocarina of Time and Majora's Mask, that he himself crafted. It was subsequently passed down through the Royal Family until it was inherited by Tetra, who is indeed Princess Zelda. The method of it's creation is never divulged.