(This is actually my first post ever on this forum, oeh, exciting!)
During the past few days, I've been reading The Hobbit and immediately, the reference to the Silmarilis hit me, when reading Bilbo's description of the Arkenstone in Smaug's lair.
At first, I was inclined to believe it was indeed one of two lost Silmarils, but after thinking about it a while, it just doesn't
fit with me. I don't truly like the idea of it.
First, I had this feeling the Silmarils should have a more, eh... grand role to play in the Ages after Melkor's defeat and the Fall of Thangorodrim. Don't get me wrong, I think Erebor's fate is important, but I don't think Tolkien would have let the Dwarves or Erebor find one of three most important jewels in the history of Arda. (Especially when you consider the rather nasty business between the Dwarves and Thingol.)
Plus, like some other people noted before, I don't think Tolkien would let the Silmaril be buried with Thorin. Again, this doesn't fit nicely to me.
But, alas, these first arguments are my pure opinion. I love to see Holy Jewels in Holy Places or deep in the fundaments of Arda, not in a Dwarf's resting place.
But to get more theoretical:
I always thought the Silmarils burned those who wanted to touch them with Bad Intentions (so, not bringing them back to Valinor).
Morgoth,
the most powerful of the Ainur, suffered from immense pains whenever he tried to touch them. Of course, Thorin isn't as dark & evil as Morgoth, but he's a mere Dwarf, when Morgoth's a very powerful ex-Vala.
The sons of Fëanor, Maedhros & Maglor, suffered, too. They also couldn't touch the gems.
So, I ask you, dear discussion partners, how could
Bilbo touch the Arkenstone, when considering it is a Silmaril? How could
the Dwarves (eg. Thorin) of Erebor have touched it?
How was
Smaug not hurt by it? I don't have my copy of the Sil right now, but I do remember Silmarils haven't got soothing effects on dragons.
The gems are hallowed by Varda, I don't think that sort of enchantment wears off after spending some time in Arda and then being spewn out by a vulcano. That sort of magic is permanent, just like Valar in themselves are. Just like the Two Trees should have been, if Melkor hadn't destroyed them.
And then, if we choose to ignore the rather tedious touching-part, wouldn't it be kind of... weird of Gandalf in the first place to just let the Arkenstone be buried next to Thorin, if he
knew it to be one of the Holy Gems? I know the Valar can't do anything with two of the three Sils, they need all three of them, but still, I think it rather obvious that they would've wanted the gem to be secured in Aman, instead of a Dwarf's grave.
Especially because Sauron is establishing his Dark Power once more in Middle-Earth. Manwë is very much aware of that; he sent the Istari to protect the peoples of ME against Sauron in the first place.
And if Sauron suddenly realized that Erebor holds
a Silmaril, one of the gems that lead to the downfall of his Master before him, that the Valar
crave for, I think he would've done everything in his power to steal it from Thorin's grave. I don't even want to think about what Sauron would've been capable of, if he owned a Silmaril.
Gandalf knows this all, so, to me, it would be, bluntly put, idiotic to leave such a power in Erebor, no matter what.
Plus, there is another person present who knows what a Silmaril looks like: Thranduil. I doubt the elf-king of the Woodland Realm would appreciate the knowledge of one of the Sils being buried with a Dwarf, Thorin Oakenshield of all people.
So, next to gut-feeling, I don't agree with the notion of the Arkenstone being one of the mighty Silmarils.
(I hope I was a bit useful.)