A vengeance demon pendant was a jeweled necklace that served as a vengeance demon's power centre. Each demon wore one around their neck and it was the source of their demonic power. The only way to reverse a vengeance demon's wish and strip her of her powers was to destroy the pendant.
There were three known pendants: the Symbol of Anyanka, Anya's original pendant, destroyed by Giles; Halfrek's pendant; and Anya's second vengeance demon pendant, when Anya reclaimed her powers. Each pendant was unique, with a different shape, size, colour and jewel.