These two small, concave glass discs have a translucent silver sheen to them.

These two small, concave glass discs have a translucent silver sheen to them. You can activate lenses of revelation to perceive the true nature of any creature in sight. Activating the lenses creates a faint aura for 1 round around the target creature (visible only to you) of a particular color based on its nature:
Evil Outsider: Red.
Undead: Bone-white.
Any Other: Green.
Any effect that would defeat a detect evil spell or effect also masks a creature from lenses of revelation.

Prerequisites: Craft Wondrous Item, augury, possession of a piece of the set.
Cost to Create: 500 gp (plus 400 gp for base item), 40 XP, 1 day.