A precious stone, mentioned four times in the Authorized Version of the Bible—twice as the translation of kadkod (Isa. liv. 12, Ezek. xxvii. 16), and twice of shebo (Ex. xxviii. 19, xxxix. 12). The Agate derives its name from the place where it was first found—the banks of the river Achates in Sicily; but it is not confined to that locality, being met with in many parts of the world. It occurs near the ancient Chalcedon, in Asia Minor (whence the name "chalcedony"), as the white Agate. The sard (brown), carnelian (red), onyx (white and black), and sardonyx (white and red) are other varieties of the same mineral. Delitzsch, "Hebrew Language," 36, connects shebo with the Assyrian shubu ("the shining").
According to Samuel bar Naḥmani (B. B. 75a), two angels, Gabriel and Michael, discussed in heaven the meaning of kadkod (Agate), occurring in Isa. liv. 12:2: "And I will make thy windows of agates ." One maintained that this precious stone is identical with beryl, while the other thought it to be a jasper. Whereupon God intervened with a paronomasia, saying: "Kadkod will contain both [ ]." According to others, the discussion took place between the Palestinian amoraim Judah and Ezekiel, sons of R. Ḥiyya; see also Pesik. R. xxiii., and Midr. Teh. lxxxvii.