Miracle Jewel is an item from Smile Pretty Cure! that contains the power of The Light of Hope, from the beginning of the story, Royal Queen hide the truth of Miracle Jewel with some bogus story about Miracle Jewel is a jewel that can make any wish come true.
Miracle Jewel was created from the full turn of Royal Clock, and the Royal Clock absorbed Candy into the Royal Clock and it became an unhatched Miracle Jewel egg, it can hatch from the power of completed set of Cure Decor.
The Miracle Jewel contains the Power of Hope and the Light of Hope, its power can be used to release the Power of Hope in the midst of despair, it also can connect with Precure's feeling of never giving up, and release the Light of Hope, it also is an item that help the Smile! Cures and Royal Candy release the power of their ultimate attack, Miracle Rainbow Burst, Miracle Jewel is the one who can connect the Earth and Märchenland, if it's power is lost, then, the Earth and the Märchenland's connection is cut.