Firestone

The Firestone was a necklace worn by Lady Clemency Eddison, a gift from her Vespiform lover Christopher. Though she believed it a mere keepsake, the Firestone was actually a powerful telepathic recorder and transmitter. (DW: The Unicorn and the Wasp)

The Firestone was stolen by Robina Redmond, although brought back when the accusations where made.

The Firestone was last seen when Donna Noble threw it into the river, causing the Vespiform to die. It was revealed in Captain Jacks Monster Files that the Firstone was recovered from the lake many years later and bought by Torchwood at an auction.