Miyuki's Crown is a tiara (moreover, a consort's crown) embedded with jewels, made to be worn around the forehead rather than on top of the head. It was once worn by Almighty Tallest Miyuki, the only known female Tallest in Irk's history. Embedded into the center of the crown is an Irken crystal; its power is what gives its wearer immortality. Miyuki did not have her crown with her when she was accidentally killed by Cthulu, Zim's energy absorbing blob creature. Although Zim was previously found guilty for her death, he was later forgiven by Miyuki's spirit, who was watching him from the Heavens along with her intended co-regent Almighty Tallest Spork.
When Zim and Gaz arrived at the palace, the crown rested on a glass pedestal within the regalia chamber.