As of now, one of the most exotic scales I can think of are those made from mammoth ivory.
But would it be possible to create some out of fossilised dinosaur teeth or claws? I imagine that these would create some very exotic scales, with a very high price.

I'm not sure how fossilised teeth or claws turn out, but if they are completely replaced by rock like bones are (I may be mistaken here), then I don't think there would be much point, since it would be very difficult to carve.

Thoughts?