The gem looked like a regular gem. It was exquisitely cut and polished. Casting detect magic on the gem was the only way to determine if it was a genuine gem of seeing. Often the gem was mounted in a frame and attached to a pole for ease of use.
The gem gave the user the ability of truesight. When an individual looked at an area through the gem, the gem detected all illusions and invisible creatures or items. It was also able to detect astral, ethereal, and phased creatures. The maximum viewing distance of the gem was 300 ft (91 m), at this range only large creatures or objects were detectable.
- One of Gamalon Idogyr's eyes acted as a gem of seeing.
- Tiztor the Great, a wizard from Mulmaster in the Moonsea area.
- Gina bint Kemala, a mystic and member of the Readers in Huzuz.
- Gershom, a ranger.
- Udall Granitecrusher, a dwarven warrior.
- Gary Gygax (1979). Dungeon Masters Guide 1st edition. (TSR, Inc.), p. 123. ISBN 0-9356-9602-4.
- slade et al. (February 1995). Encyclopedia Magica Volume II. (TSR, Inc.), p. 528.
- Monte Cook, Jonathan Tweet, Skip Williams (July 2003). Dungeon Master's Guide v.3.5. (Wizards of the Coast), p. 257. ISBN 0-7869-2889-1.
- Mike Mearls, Jeremy Crawford, Christopher Perkins, James Wyatt (2014). Dungeon Master's Guide 5th edition. (Wizards of the Coast), p. 172. ISBN 978-0786965622.
- David "Zeb" Cook (1989). Dungeon Master's Guide 2nd edition. (TSR, Inc.), p. 170. ISBN 0-88038-729-7.
- Gary Gygax (1979). Dungeon Masters Guide 1st edition. (TSR, Inc.), p. 145. ISBN 0-9356-9602-4.
- Steven E. Schend (1997). Lands of Intrigue: Book One: Tethyr. (TSR, Inc.), p. 86. ISBN 0-7869-0697-9.
- John Terra (November 1997). Four from Cormyr. (TSR, Inc), p. 68. ISBN 0-7869-0646-4.
- Tim Beach, Tom Prusa and Steve Kurtz (1993). Al-Qadim: City of Delights (Golden Huzuz). (TSR, Inc), pp. 55–56. ISBN 1-56076-589-5.
- Rick Brown, James Ward (1991). AD&D Trading Cards 1991 series, #523, "Gershom". TSR, Inc..
- Rick Brown, James Ward (1991). AD&D Trading Cards 1991 series, #609, "Udall Granitecrusher". TSR, Inc..