Adam Clarke on Exodus 28:11

Like the engravings of a signet - So signets or seals were in use at this time, and engraving on precious stones was then an art, and this art, which was one of the most elegant and ornamental, was carried in ancient times to a very high pitch of perfection, and particularly among the ancient Greeks; such a pitch of perfection as has never been rivaled, and cannot now be even well imitated. And it is very likely that the Greeks themselves borrowed this art from the ancient Hebrews, as we know it flourished in Egypt and Palestine long before it was known in Greece.