Marquiseire is an unmapped star that is illegal to bottle. It is described to emit a rosy light, which is pink and glittery when used to light leap. Sophie, Keefe, and Sandor are given a bottle of Marquiseire's light to light leap by the Black Swan in Everblaze, and Mr. Forkle uses it to leap from Atlantis to Alluveterre in Neverseen. Marquiseire's light is the only type of light that makes it possible to leap from underwater.
Leaping in it feels like "each glinting speck turned coarse as they traveled--grating and scraping, like they were leaping through a glitter bomb."
Mr. Forkle explains that the Quintessence from Marquiseire is "incredibly abrasive, which makes it the best choice when something needs to be broken down on a cellular level." Its abundance of shimmer also makes it reflective, which allows it to be the most versatile of all the iterations of the fifth element. He says that the elves have only scratched the surface of its many uses.