The third stone of this row is the "diamond" or adamant; and that this stone is meant seems clear from its name Jahalom, which comes from a word which signifies to break; and from hence a hammer has its name, because this stone pierces, cuts, and breaks other stones, but cannot be broken itself.
On these three stones were engraved, according to the Jerusalem Targum, the names of the three tribes of Judah, Issachar and Zebulun; but more truly, according to the Targum of Jonathan, the names of the tribes of Judah, Dan and Naphtali, and so Jarchi; for the names here, as on the onyx stones, were according to the order of their birth.
Ut supra, (Nat. Hist. l. 37.) c. 5. Ut supra, (De Vestitu Sacerd. Heb. l. 2.) c. 11. sect. 2, 7. p. 661, 667. De Gemmis, l. 2. c.