Quartz is a female Koopa with sharp canine teeth and a shell that actually ranges in color from pinkish red to maroon. It changes constantly for reasons unknown. She has teamed up with Corundum to dominate the universe. She is one of the villains in Paper Mario: The Diamonds of Virtue.
Quartz fabricated the clear Diamond of Corruption so that she can have extraordinary power in stopping anyone who gets in her and Corundum's way, even anyone who opened the "ancient lock" on the gateway to their base by collecting all the Diamonds of Virtue.