Fausset's Bible Dictionary
odem , i.e. "the red stone" (with a yellow shade). Exodus 28:17; Exodus 39:10; Ezekiel 28:13. Much used by the ancients for seals, as being tough yet easily worked, beautiful, and susceptible of high polish; the best stone for engraving. Josephus (the best authority, being a priest, therefore having often seen the high priest's breast-plate) calls it the sardonyx, the first stone in the high priest's breast-plate, in Ant. 3:7, section 5, but the sard or sardine, B.J. 5:5, section 7. Both sardine and sardonyx are varieties of agate. He on the heavenly throne "was to look upon like a jasper and a sardine" (Revelation 4:3). As the jasper (or else diamond) represents the divine brightness or holiness, so the red sardine (our cornelian) His fiery wrath; the same union as in Ezekiel 1:4; Ezekiel 8:2; Daniel 7:9. Named from Sardis in Lydia, where it was first found. The Hebrew got their high priest's sardines in Arabia, and from Egypt (Exodus 12:35).
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Fausset, Andrew R. Entry for 'Sardine'. Fausset's Bible Dictionary. https://www.studylight.org/dictionaries/eng/fbd/s/sardine.html. 1949.