Gem of Seeing is a rare wondrous items in D&D 5e. It requires attunement.
Wondrous item, rare (requires attunement)
This gem has 3 charges. As an action, you can speak the gem's command word and 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.