The Glittering Beljuril Gemstone is the item described by Avarice, one of the four dwarven wards guarding the stairs to Labyrinth Level 2 of Durlag's Tower. You must give it to him as part of the process to advance to the next lower level.
You have completed this riddle. I am AVARICE. I will bring doom upon you in this cursed place.
This stone seems to be out of place down here, almost as if it wasn't a coincidence at all. Perhaps it has some meaning, maybe even a purpose here. You get an uneasy feeling that this gemstone shouldn't be sold; perhaps it would be best not to be too greedy and keep it around awhile. Normally a deep, pleasant seawater green, beljurils periodically blaze with a glittering, winking, flashing light. However, this particular stone has a slightly different hue; perhaps it is a new strain, rarely if ever seen before. It looks incredibly valuable.