Thorin vows to kill anyone who withholds the Arkenstone .
Spoiler Alert! Thorin is laid to rest under the Lonely Mountain with the Arkenstone on his breast.
The Arkenstone is a large white gem sought by Thorin Oakenshield in The Hobbit . It was discovered beneath Erebor (the Lonely Mountain) by Thorin's ancestor, ThrÃ¡in the Old, and shaped by the Dwarves .
I think that it is the Arkenstone but I'm not sure.
Bilbo takes possession of the Arkenstone without telling Thorin.
He starts looking through the treasure for the Arkenstone.
Smaug has the Arkenstone in his hoard. Bilbo acquires it from the pile of treasure. He then gives it to Bard. Bard puts it with Thorin when he is buried. That is where it stayed.
When Thorin was entombed in the Lonely Mountain, Bard laid the Arkenstone upon his breast.
The Arkenstone, the Heart of the Mountain. It was the only piece of treasure that Thorin coveted.
Thorin covets the Arkenstone, which he believes to be his birthright and legitimise his claim as king under the mountain.
Thorin was not truly greedy, but the Arkenstone held a sway over him that made him act in a selfish manner.
Bilbo took the Arkenstone. It was the treasure Thorin desired most.