Ethereal Gem

Ethereal Gems specify the particle effect of custom couriers. A Prismatic Gem on the same courier will alter the color of most effects.

Socketing
Ethereal gems can only be placed in an Ethereal socket; couriers, found from Treasures, are the only items that have an Ethereal socket. Ethereal Gems can only be extracted with a Master Artificer's Hammer. Doing so will destroy the courier. When applying an Ethereal gem to an item, the new gem will destroy the existing one.