Laeral's tears

Laeral's tears was the Realms name for beryllonite, named after the famous sorceress Laeral Silverhand.

Description
This gemstone was soft and brittle but deposits often produced large crystals which could be facet cut into impressive colorless gems  that held a glossy, lustrous shine. A typical specimen had a base value of 100  to 200 gp.

Powers
It was a little known fact that this fancy stone was one of the "nine secrets" that could be turned into an Ioun stone. Of the nine gems, Laeral's tears was the rarest.

The upper echelons of the witches of Rashemen had a secret use for this gem. Through a complicated process of treatment and spellcasting, Laeral's tears could instantaneously heal wounds sustained in battle. The subject had to be wearing the gem for the protection to work, and once it healed its quota of damage, the stone shattered and became useless.