Truthie glimaerstone

Sometimes a very special rare glimaerstone is set into jewelry. They change in the light. If you cast 205, Light, at it, it will glow brightly. It also changes its description if you're outside, depending on the light.

From the old notes at play.net about glimaerstones:

Although Winedotter gnomes are not noted for their jewelcraft, one Winedotter family living beneath Ta'Nalfein discovered a technique for enhancing the light of a glimaerstone. The source of these specially treated glimaerstones is not extensively known, and most outside Ta'Nalfein believe them to be elven work. This technique somehow quenches the natural glow within a glimaerstone and replaces it with a remarkable ability to absorb and multiply light. At their brightest degree, such "treated" glimaerstones will leave afterimages in the vision of those who look at them for too long. Regrettably, most of the family died in 5102 in a tragic accident involving an overturned candle and a remarkable quantity of excellent brandy, leaving only the eldest daughter alive. More regrettably still, this eldest daughter (commonly nicknamed Truthie) is apparently quite mad and utterly unwilling to take on an apprentice. Knowledgeable jewelers have been storing away treated glimaerstones in anticipation of the day when the source dries up.

It does not spam the room when the light description changes, unlike the forehead gems.