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.
yes
The Arkenstone is the jewel of main focus in The Hobbit, and it's a prized treasure among the dwarves.
The Arkenstone
Bilbo took the Arkenstone from Smaug's treasure trove. He gave it to the men to use as a negotiating tool.
It is the most prized jewel of the Dwarves
kill em.
He was entombed under the Lonely Mountain. He was laid to rest with his sword and the Arkenstone.
The Arkenstone does nothing. In fact, the only reason the dwarves want it back is because it is a great treasure and a magnificent jewel. It was discovered beneath the roots of the Lonely Mountain and is also known as the heart of the mountain.
Bard keeps the arkenstone and will give it back to Thorin later if he can receive part of the share
Bilbo snuck out of the Dwarves camp and delivered the Arkenstone to Bard.
He forgives Bilbo for stealing the Arkenstone, and then tells Bilbo that everyone should be like the hobbits: more concerned with comfort than with treasure. Then Thorin dies. He is buried with the Arkenstone, and Dain, Thorin's cousin, is proclaimed the new king.
Gandalf was looking for someone to share in an adventure at the beginning of The Hobbit.