I don't think he cared about the silmarils themselves at all. It was simply being a possession of his dead father and his oath that made him care.

I feel like it's an underrated bit of characterization that, of all metals, he loved COPPER.

Copper, while lovely, is soft and maleable and by it's nature will oxidize over time to become blue-green and so is doomed to change no matter what (time will change it's color, polish and care will wear it away a bit at a time until it's no more).

And Maedhros ended up doomed and changed irrevocably himself, like the copper he favored over the eternal and shining gold and silver everyone else loved.

I don't think there's any other character described as loving copper, or even favoring anything except gold and silver (and mithril which looks like silver) for metals, but especially not an elf.

There is no way any piece of jewelry worn by Maedhros could have truly survived in the state it was in when he wore it. It's all either altered in some fundamental way visually, or it's literally gone. Eroded by either time or the hands trying to battle back time to keep it pristine.

I feel like his love of copper is a foreshadow of both how he would change and be changed by the "oxidization" of Beleriand and also how he himself is capable of letting go of the silmarils because ALL of his favored jewelry is fated to be gone eventually, so he was always able to let go of material things, in perhaps a way no other elf could.

Headcanoning that he would ALWAYS have destroyed the silmarils after acquiring them.

The other sons of Feanor wanted to possess them again and end the silmaril conflict by returning them to the House of Feanor they belonged to, but Maedhros was quietly planning to have a true and final end to the conflict they bring by smashing the fucking things from the start.