Corundum is a Yoshi with sharp canine teeth and a tomato red color. He has teamed up with Quartz to dominate the universe. He is one of the villains in Paper Mario: The Diamonds of Virtue. Corundum fabricated the rainbow Diamond of Corruption so that he can have extraordinary power in stopping anyone who gets in his and Quartz's way, even anyone who opened the "ancient lock" on the gateway to their base by collecting all the Diamonds of Virtue.