Not much is known about the Artifacts/Warehouse 14/Pearl of Wisdom aside from the manipulative effect it has on its victims.
The user places the Pearl in the ear of an intended victim, where it attaches to the brain. The process induces terrible nightmares in the victim, and once attached, allows the person who placed the Pearl to control the thoughts and actions of the victim.
The Pearl can only be removed by bringing the victim to the point of death, whereby the Pearl detaches itself from the victim's brain and rolls out of the ear canal.
The Pearl can be manipulated by a large, unnamed Amber Orb to explore the memories of the person with the Pearl in their ear.
A 'pearl of wisdom' is an idiom in the English language, meaning a succinct, insightful saying, piece of information, or moral precept.