- You may be looking for the Crown of Rassilon.
The Coronet of Rassilon was one of the many artefacts created by Rassilon, similar to the Crown of Rassilon. It was one of the items worn by a President of Gallifrey as a symbol of office. When worn, the Coronet enabled domination over the will of others. The Fifth Doctor also deemed it a "very fetching" piece of jewelry. (TV: The Five Doctors)
Morbius wore the Coronet during his time as Lord President in his first incarnation. When the High Council deposed him, he was publically stripped of it (as well as of the Sash of Rassilon and the Rod of Rassilon) by then-Junior Cardinal Borusa. (PROSE: Warmonger) As Lord President himself, a later regeneration of Borusa would himself use the Coronet to impose his will onto the Fifth Doctor, but this was broken by the mental power of the First, Second, and Third Doctors. Borusa also paralysed the Brigadier, Sarah Jane Smith, Susan Foreman and Tegan Jovanka when he told them not to move or speak until spoken to; they were freed when Borusa was imprisoned within Rassilon's sarcophagus. (TV: The Five Doctors)