Wondrous Item, Rare (Requires Attunement)
This gem has 3 charges. As a Magic action, you can expend 1 charge. For the next 10 minutes, you have Truesight out to 120 feet when you peer through the gem.
The gem regains 1d3 expended charges daily at dawn.
Source: SRD 5.2.1 · CC-BY-4.0