The Pearl of Wisdom is a pearl enclosed inside a crystal oyster that gives anyone wisdom. It first appeared in "Knick Knack Paddy Whack". The Glooms steal it so that Hildy could win a radio contest with a diamond-encrusted silk cloak as its prize to best her rival, Snazzy Shazam.
In the show
The 7D found the Pearl of Wisdom at the Enchanted Sea and later gave it to Queen Delightful as a gift, and is being stored at her room full of knick knacks. Later, Hildy learns of a contest whose its grand prize is a silk cloak with diamonds on it by correctly answering a riddle before sundown ("What do you call a witch at the beach?"). Through their Crystal Ball, the Glooms learn about the Pearl of Wisdom that grants an answer to any question.
The Glooms broke into the castle and stole the pearl. Back at their manor Hildy went through much difficulty trying to open the pearl, though Grim mentioned from the Book of Spells that the Pearl of Wisdom can only be opened by saying the "magic word". The 7D arrived disguised to sell various goods to the Glooms, while Bashful goes inside to retrieve the pearl. After their cover was blown, the Glooms gave chase to the dwarfs. The pearl passed through several hands during the chase; it finally ended up with Grim, who afterwards crashed into the mud pit on his riding mop.
Grim asked for the crystal oyster to be opened, and after saying the word "please", it finally does so. The Pearl of Wisdom then allowed him to ask a question. Grim asks where Hildy is, and the pearl responds that she's right beside him. While Hildy is furious at her husband who ruined her chance at winning the contest, Snazzy flies by and shows them her prize. Dopey and Sleepy plucked the Pearl of Wisdom from Grim's hands and it returned safely to the Queen.