Salazar Slytherin's Locket was originally owned by Salazar Slytherin and became an heirloom of his family. It was a locket of heavy gold with a serpentine S in glittery green stone inlay on the front.
In 1997, Albus Dumbledore and Harry Potter ventured to the seaside cave where Voldemort had hidden his locket. They were fairly certain that a Horcrux was hidden in the cave. Through great personal injury, Dumbledore successfully retrieved the fake locket Black and Kreacher had
Original Pattern and can be found here
Dragonsinger of Hufflepuff