Gems of Power

The Protective Jewelry was given to Finn and Jake by Princess Bubblegum. Princess Bubblegum, along with possible other princesses and royalty in Ooo, wears this jewelry. The protective qualities of the jewelry are seemingly in the gemstones. The jewelry grants the wearer protection from The Lich's powerful spells. Finn's jewel breaks during his encounter with the Lich, almost causing the Lich to gain control of Finn. However, Finn was still protected by the sweater he was wearing.