Prism of Separation

Wondrous item, very rare

This glass object separates light like any other prism, but may also be used to reduce the effectiveness of ray spells if worn openly. If you are targeted with a ray attack, it does not affect you. In addition, there is a 10% chance that a ray spell that would have hit you is reflected back to its source. If the source was a creature that can see, it must succeed on a DC 16 Constitution saving throw or be blinded for 1d4 rounds. If you hurl the prism at a prismatic wall, it destroys it, but then loses its powers permanently, turning into a 3,000 gp gem.