The Queen's bell is a special silver pendant used as a means of summoning for the Queen of the Seelie Court. It was a tiny silver pendent with a chain loop at the end of the handle. Ringing the bell makes it easy for the holder to contact the Queen—it would alert the Queen, and, if she were present and ready to receive them, the person would then be brought to the Court.
The Queen, knowing that Clary Fray would one day need her help despite the latter's stubbornness, had one of her Court ladies, Kaelie Whitewillow, give the bell to the Shadowhunter. Kaelie went to the engagement party of Clary's mother, Jocelyn, and Luke Garroway to give her the bell, using Jace as a way to entice her into considering the prospect of using it to ask the Queen for help in the future. Knowing the Folk's cunning nature, Clary was hesitant, but she still found herself accepting the bell. Kaelie immediately left before Clary could refuse and return it.
For the first few weeks of Jace Herondale's disappearance with Sebastian Morgenstern, Clary contemplated using the bell, to the point where she began wearing it as a necklace on the chain that once held her Morgenstern ring. Eventually, just as the Queen expected, Clary became desperate enough that, with Simon, Isabelle and Alec's reluctant approval, she finally rung the bell. The group was then transported to the Faerie.