Karatek's coronet was an artifact of Vulcan origin and present within Romulan society.

It was created on Vulcan by the Priest-Kings of the Te-Vikram Brotherhood but later found its way into the hands of the Adepts of Gol and those adepts at Mount Seleya. When Surak journeyed to meet the adepts, one of his companions was the scientist Karatek. The device had the power to record mental thought within it allowing for a persons memory to be recorded and recalled by a Vulcan using the coronet. Taking the coronet with him, Surak gifted the crown to Karatek during the time of the Sundering with the intention of Karatek being the keeper of the artifact as the Vulcan Exiles sought to find a new home.

Karatek used it to record his thoughts during the journey to find their new home; noting down the losses they fleet faced and the hardships they suffered from during the exodus. After reaching the twin worlds of Romulus and Remus, Karatek and his followers were exiled to Remus where he continued to make records of his hardships. When he helped in a secret attempt for some of his people to escape from Remus, he intended to pass the coronet to his adopted daughter Sarissa. However, in an attempt to allow them to escape, he had to sacrifice his life and the coronet fell into the hands of the early Romulans. The coronet became an artifact within the Romulan Star Empire in later centuries though its true nature was unknown to many.

In 2377, the descendants of Sarissa's people called the Watraii launched an attack against the Romulan Star Empire after the events of the Dominion War with the intention of claiming the coronet back as well as Romulus which they believed was their usurped homeworld. Ambassador Spock by using the coronet managed to learn the history of the Romulans and Remans as well as the origins of the Watraii. During the short conflict, a peace was negotiated and the coronet was to be returned to Vulcan as it was intended by Surak. (TOS - Vulcan's Soul novels: Exodus, Exiles, Epiphany)

It was never given a formal name throughout the novel series and was simply referred to as the Coronet.
Community content is available under CC-BY-SA unless otherwise noted.