Silmarils
 

how do you think the silmarils look like??

I imagine them as sort of palantir looking (like a perfectly round globe) but with great white-yellowish radiance.

It's a cop-out I know, but I reckon any attempt to describe the silmarils is pointless, as I imagine them to be beautiful beyond our comprehension. I am inclined towards the idea that their shape is almost irrelevant; it was the light they contained (the light of the Trees) that characterized and defined the silmarils, a light so boundlessly captivating that the Noldor destroyed themselves trying to get the silmarils back.

Just my opinion; on the other hand they could look like large rubies :)

Well, I’ve always imagined the Silmarils as star-like in both light and shape.

I always imagined them as large diamonds. Many-faceted, clear, somewhat white-shining. Though it contradicts what was said about them and my image of them is just very, well, simple :)

Seeing that both Feanor and Earendil wore a silmaril on their brow (Feanor all three), I would expect them to be quite small..

Perhaps they just had large heads :p :D

But yes, that's interesting, I never thought about it. It's true the Silmarili had to be also at maximum of the size to be hidden inside a man's hand - though probably a big and strong adult man's hand. I always imagined them quite big, though - indeed, about the size of a man's closed fist. What you said however implies they were a lot smaller - unless they were to function like a cap peak.

I imagined them being quite like you Legate "large diamonds. Many-faceted, clear, somewhat white-shining" but even though I pictured them as white-shining, they can shine in all kinds of colours. garr it is hard to describe!

I really do like that cold white light of the stars, but I imagine that when you glance at the silmaril again it would seem slightly different.

Anyways a large diamond would still be small enough for you to carry it upon your brows.

Well yes, but being 3-D it would stick quite far in front of your forehead. And also, there was this thing Raynor said about Fëanor wearing three of them.

Yes, that's exactly how I picture them. Small diamond shaped crystals and the radiance from it makes them seem larger than they really are.

Not necessarily. . . if your craftmanship is good enough you can definitly make it work, even with quite big stones.

When feanor had them all three is am sure he had diadem/crown like arangement going on.

Well, I think he would look kinda silly with a big mine-worker like thingie, shinning on his bobbing head. Although I believe that Legate's presupposition is thirteen kinds of awesome :D
He is definitely the winner of this thread :p

I always pictured them as being about the size (and approximate shape) of half a golf ball. Maybe a tennis ball. :) If they were intended to be jewels to be worn, they would need to be shaped in such a way that they could fit into a setting that could be comfortably worn. And the silmarilli are frequently described as being worn -- in Morgoth's crown, in the Nauglamir, on Earendil's brow, etc. Given Feanor's ego, I always felt that he would have wanted to be able to wear his greatest creations, and would have made them in a shape (more or less hemispherical) easily placed in a setting. Tolkien's drawings of them in his heraldic devices shows them as looking, in shape, like six-pointed stars in circles, which could be his way of indicating that they were also faceted.