Onyx stones, or, sardonyx stones. Note, that the signification of the Hebrew names of the several stones are not agreed upon by the Jews at this day, and much more may we safely be ignorant of them, the religious use of them being now abolished. Stones to be set in the ephod; stones of fulness, or filling, or perfecting stones; so called either because they did perfect and adorn the ephod, or because they filled up the ouches, or the hollow places, which were left vacant for this purpose. What the ephod and breastplate were, see Exo 28.
Related Commentaries of Exodus 25:7
Exodus 25:7
7 Onyx stones, and stones to be set in the ephod, and in the breastplate.