This crystal appears to be nothing more than a gem in rather rough, long prismed shape. 

Upon utterance of the proper spell words, however, the crystal will emit bright light of 3 sorts. 

— It can be caused to shed a pale light in a cone-shape 10-ft long, emanating from the gem to a radius of 2½-ft at the end of the beam. This does not discharge any of the energy of the device. 

— Another command will cause the gem of brightness to send out a very bright ray of light of only 1-ft diameter but of 50-ft length, and any creature who is struck in the eyes by this beam will be dazzled for 1-4 rounds and unable to see. The creature struck is entitled to a saving throw versus magic to determine whether or not its eyes were shut or averted in time. This use of the gem expends 1 energy charge. 

— The third manner in which the item may be used is to cause it to flare in a blinding flash of light in a cone 30-ft long and 5-ft radius at its terminus. Although this glare lasts but a moment, all creatures within its area must save versus magic or be blinded for 1-4 rounds and thereafter suffer a penalty of -1 to -4 on hit probability dice rolls due to permanent eye damage. This use expends 5 charges. 

Dazzling or blindness effect can be removed by a cure blindness spell; eye damage can be cured only by a heal spell. 

The gem of brightness has 50 charges and cannot be recharged. 

A darkness spell will drain 1 of its charges, or make it useless for 1 round, at the option of the gem owner. 

A continual darkness spell will cause it to be useless for 1 day, or expend 5 charges, at the option of the owner.