system
Given the following post, respond as if you're commenting on Reddit:
human
[Lord of the Rings] What are the Silmarils and what can they do?
gpt
They are the most beautiful jewels ever crafted. Most beautiful crafted things ever, actually, created bt the greatest crafter of all times.


They capture the primordial light of the two trees that lighted the world before sun and moon existed and their beauty can be seen through them.

As for what they can do - not much, really. They are not practical things. 
They could have been potentially used to restore the two trees after they were killed, but it was never attempted, and the silmarils would have been destroyed in the process even if it worked.

Oh, and the only surviving silmaril is the morning star, so there's that.