maboroshi no ginzuishou
A key artifact from the Bishoujo Senshi Sailor Moon series. It is a silver crystal containing immense holy power that only members of the Moon Family can wield, but relying upon it during dire situations can put the user's life in danger. It was first used by Queen Serenity, then passed to her daughter Princess Serenity, and from there will be inherited by Small Lady Serenity.
It may or may not be seen on the Moon Stick.