Arkenstone of Erebor, The
But fairest of all was the great white gem, which the dwarves had found beneath the roots of the Mountain, the Heart of the Mountain, the Arkenstone of Thrain.
"The Arkenstone! The Arkenstone!" murmured Thorin in the dark, with his chin upon his knees. "It was like a globe with a thousand facets; it shone like silver in the firelight, like water in the sun, like snow under the stars, like rain upon the Moon!"
The Hobbit-Inside Information-pg. 243
was the Arkenstone, the Heart of the Mountain. So Bilbo guessed from Thorin's description; but indeed there could not be two such gems, even in so marvellous a hoard, even in all the world. Ever as he climbed, the same white gleam had shone before him and drawn his feet towards it. Slowly it grew to a little globe of pallid light. Now as he came near, it was tinged with a flickering sparkle of many colours at the surface, reflected and splintered from the wavering light of his torch. Atlast he looked down upon it, and atlast he caught his breath. The great jewel shone before his feet of its own inner light, and yet, cut and fashioned by the dwarves, who had dug it from the heart of the mountain long ago, it took all light that fell upon it and changed it into ten thousand sparks of white radiance shot with glints of the rainbow."
The Hobbit-Not At Home-pg. 249
"For the Arkenstone of my father," he said, "is worth more than a river of gold in itself, and to me it is beyond price. That stone of all the treasure I name unto myself, and I will be avenged upon anyone who finds it and witholds it."
The Hobbit-A Thief in the Night-pg. 279
It was as if a globe had been filled with moonlight and hung before them in a net woven of the glint of frosty stars.
"This is the Arkenstone of Thrain," said Bilbo, "the Heart of the Mountain; and it is also the heart of Thorin. He values it above a river of gold. I give it to you. It will aid you in your bargaining." Then Bilbo, not without a shudder, not without a glance of longing, handed the marvellous stone to Bard, and he held it in his hand, as though dazed.
The Hobbit-AThief in the Night-pg. 283-284
"What of the Arkenstone of Thrain?" said he, and at the same moment the old man opened the casket and held aloft the jewel. The light lept from his hand, bright and white in the morning.
The Hobbit-The Cloud Burst-pg. 286-287