The amulet necklace given to Dean Winchester
by his brother Sam Winchester
when they were kids, on the show Supernatural
It's called the Samulet as a combination of the name Sam and the word amulet.
It was borrowed by Castiel
in the fifth season, as he was searching for God and it was supposed to burn white hot in God's presence. It didn't work and Castiel returned it in the episode "Dark Side Of The Moon."
Dean, for some reason not understood by fans, threw it away, despite obvious sentimental value.
Sam gave Dean the Samulet when they were kids.
The Samulet was supposed to burn in God's presence, but it turns out it was worthless.