An aigrette is a a "spray of jewels or feathers, worn on a hat or in the hair." (Websters) The Nadiri aigrette is one of the many aigrettes in the Iranian crown jewels collections. It is 13 cm. (5 in.) tall and has a 65 ct. emerald in its center, possibly of Columbian origin.
Despite its name, the Naderi aigrette was probably not worn by Nader Shah, since there are no references to it before the Qajar dynasty.