Item from harry-potter-deathly-hallows by
Heavy gold Horcrux that whispers your worst fears while you wear it -- it drove Ron to abandon his friends and showed him visions of Harry and Hermione together before he destroyed it with the Sword of Gryffindor.
The locket's journey is the spine of the Horcrux hunt. Stolen from Umbridge at the Ministry. Worn in rotation by Harry, Ron, and Hermione while camping. It poisoned Ron first -- whispering that he was the least important, that Hermione loved Harry, that his mother wished he'd died. Ron left. The Deluminator brought him back. Harry opened the locket with Parseltongue in a frozen forest pool, and the Horcrux erupted -- showing Ron a vision of Harry and Hermione together, mocking him, confirming every fear the locket had been whispering for months. Ron destroyed it with the Sword of Gryffindor anyway. The most important swing of his life, and he made it shaking and terrified and furious and brave.
Large heavy gold locket with a serpentine S in glittering green stones. Opens only to Parseltongue. When worn, it whispers to the wearer, amplifying jealousy, fear, and self-loathing. When threatened, it projects illusions of the wearer's deepest insecurities.
Also known as: Slytherin's locket, the locket