What was the Arkenstone?

[the guy who be short]

Interesting, but I don't think Thrain was senile (I assume your post was in jest, shorty

Yes, my post was a joke. Can't really imagine a senile dwarf. Also, please refrain from calling me shorty. I dont mind TGWBS though.
There is now no chance the Nimphelos was the Arkenstone. I have no evidence other than that already stated, but do not believe it was a Silmaril.