[Shelob]

I know it, and I didn't think it was too confusing.

It's the Arkenstone

"It was like a globe with a thousand faces; it shone like silver in the firelight, like water in the sun, like snow under the stars, like rain upon the Moon!" (The Hobbit, Chapter XII Inside Information)

so it is "Shining as sunlight,/and with the light of the stars,"
and

"They buried Thorin deep beneath the Mountain, and Bard laid the Arkenstone upon his breast." (The Hobbit, Chapter XVIII The Return Journey)

so that it's "now kept in the deep"

hmm...I guess this means I've got to come up with a Haiku...give me a day or so, I'll have one by then.

Many Thanks.