Ioun stone

Ioun stones, originally called Congenio's pebbles, were magical stones that granted enhancements or powers to a creature.

Description
They were small, crystalline stones, coming in a wide range of colors and shapes that determined their powers.

Powers
Ioun stones hovered permanently in the air.

When one acquired a stone and wished to receive its benefits, they had to first hold it for a brief time and then release it. Thereafter, when functioning, the ioun stone floated in a circular pattern around the bearer's head, at a distance of 1–3 ft (30–91 cm). They could only bestow their benefit on an owner when within this range. Two stones of the same type would repel each other. Another person could try to catch or net the stone to steal it, or break it. The bearer could freely grab and pocket a stone, such as when going to sleep, to keep it safe, but they could no longer receive its benefits.

The stones granted various benefits based on their color, as listed below. When drained of power, a stone became a dull grey, but it still possessed the characteristic floating power.

Creation
Ioun stones could only be created by a veteran spellcaster well versed in the crafting of wondrous magical items.

History
Congenio Ioun, an arcanist of Netheril, created the first ioun stones.