Chalcedony

Chalcedony was a type of glass-like rock that had either a milky translucence, or, in some cases, a darker color. Statues would be sculpted in chunks of chalcedony: the tessent idols of Alsakan were made of it, and so were effigies of Borz'Mat'oh and Fillorean at the University of Coruscant. On the planet of Alderaan, chalcedony was strongly associated with the House of Organa, who used it as a signet of office. At the time of the Great Galactic War, the ruling lord of the House was referred to as the "heir to the chalcedony star." Additionally, the Royal Chalcedony Shield, a medal awarded by the High Council of Alderaan to worthy off-worlders, was also made of chalcedony.

Text and facts from the “Chalcedony/Legends” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.