[σάρδιος] properly, an adjective from an uncertain base; sardian (3037 being implied), i.e. (as noun) the gem so called
Usages throughout the bible
Revelation 21:20
-
The fifth, sardonyx; the sixth, sardius; G4556 the seventh, chrysolite; the eighth, beryl; the ninth, a topaz; the tenth, a chrysoprasus; the eleventh, a jacinth; the twelfth, an amethyst.