These earrings are unusual. Not sure if they are the prettiest things but definitely unusual construction and the back is rough. I do see a mark, it looks like T 90 or T 09? 06? 60? Maybe what looks like a T to me is just part of the "roughness" of the back of these. Unfortunately trying to search numbers for markings is not leading me anywhere.
Any clues?
Thanks as always! 
