Cerulean gemstone

Cerulean gemstones were a type of cerulean colored gemstone that were embedded into the bodies of Kashyyyk clarions by the Wookiees of the planet Kashyyyk.

Behind the scenes
Cerulean gemstones were first created as a prop for the film Star Wars: Episode III Revenge of the Sith, although they are not visible in the final cut of the film released in 2005. The gemstones then first appeared in canon in the 2016 reference book Star Wars: The Visual Dictionary, which was written by Adam Bray, Tricia Barr and Cole Horton. In Legends, the gemstones had previously appeared in the 2005 reference book Star Wars: Revenge of the Sith The Visual Dictionary, which was written by James Luceno.