Lewis & Short

sardĭus, a, um, adj. [cf. 1. sarda, II.], sardian, carnelian (late Lat.): lapis, Vulg. Exod. 28, 17.
Hence, subst.: sardĭus, ii, m., the carnelian, a precious stone, Vulg. Exod. 39, 10; id. Apoc. 21, 20; Tert. adv. Marc. 2, 10; called lapis sardinus, Vulg. Apoc. 4, 3; cf. Hier. in Isa. 15, 54, v. 11 sq.