Shaded Spectacle is made from two Polarized Glass
https://ffxiv.gamerescape.com/wiki/Polarized_Glass
It is rare drop from only two submersible destinations or chests from a Leather Buried Treasure Map, obtained from an Unhidden Leather Map which itself is a very rare drop from any ARR/HW chest found by ARR/HW Timeworn Treasure Maps.
That is why it's generally fairly expensive on the market board.

https://ffxiv.gamerescape.com/wiki/Shaded_Spectacles