[MLD-Grounds-Keeper-Willie]

Well, JRRT came out with The Hobbit before the Silmarillion. So, the arkenstone was, in reality, created (by JRRT) before the silmarils were. If JRRT wanted to have the arkenstone be a silmaril, then he would not have made the point that the silmarils could not be fasioned or cut, as the arkenstone was.

And I agree with The Saucepan Man in regards to taking the Hobbit serious in it's text. it was written by JRRT, so why should we disregard it? If anything, we should disregard text from the Silmarillion, since although JRRT did write it, Christopher Tolkien edited it.