Mykaro

Mykaro, also known as smithsonite, was a massive gemstone found in many hues as crystals or as crusts up to 2 in (5 cm) thick in rock cavities.

Description
These semi-precious stones were soft and durable when found as a crust, but brittle in crystal form. The varieties of color included yellow, straw yellow, pale brown, reddish brown, green, blue, and blue-green. It was usually cut cabochon, particularly if it was patterned with thick bands of varying colors, but was sometimes faceted. A typical specimen had a base value of 50 gp.

Powers
These stones, regardless of color, were part of an unusual cure for blindness that worked even if the eyeballs had been destroyed. A mykaro stone was ground to powder and added to any nonalcoholic beverage. Then a wizard able to cast wizard eye immersed the invisible sensory organ created by that spell into the mixture and then removed it. If the afflicted person consumed the magically charged drink within 10 minutes, their blindness was cured in a matter of a few seconds. If the eyeballs were missing, they regenerated in about 10 minutes, at which time the person's vision was restored.