Troll's clothes?

[Hot, crispy nice hobbit]

Gee, I suppose the Invisibility part can be explained in that the Ring just pulled the wearer into the "spirit world" together with his/her belongings.

"You were in gravest peril while you wore the Ring, for then you were half in the wraith-world yourself, and they might have seized you.'

One interesting note, when Bilbo was wearing the Ring in the Files and Spiders of The Hobbit, he wielded the Sting and slashed through the spider webs. The spiders could not see Bilbo, but they saw the Sting!

Out came his little sword. He slashed the threads to pieces and went off singing. The spiders saw the sword, though I don't suppose they kew what it was, and at once the whole lot of them came hurring after the hobbit along the ground and the branches, hairy legs waving, nippers and spinners snapping, eyes poping, full of froth and rage.

But let's get back to the question: Did the trolls' clothes turned into stone? Maybe those clothes were made of the hide from other Trolls?