Estimated Value (Sane Cost Guide): 32,000 gp
DMG Value: 501 gp - 5,000 gp
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.
Source: DMG p172