Diamond

Diamond appears four times in the King James Bible, and it is not always the stone we know. It sits in the second row of the high priest’s breastplate, between the emerald and the sapphire, set among stones that stood for Israel’s tribes. Ezekiel lists it among the jewels that covered a proud king in Eden. Jeremiah uses it for something harder, saying the sin of Judah is written “with a pen of iron, and with the point of a diamond.” Whatever stone it was, the point is its hardness. See Exodus 28:15-21.

4 verses

Exodus

Exodus 28:18

And the second row shall be an emerald, a sapphire, and a diamond.

Exodus 39:11

And the second row, an emerald, a sapphire, and a diamond.

Jeremiah

Jeremiah 17:1

The sin of Judah is written with a pen of iron, and with the point of a diamond: it is graven upon the table of their heart, and upon the horns of your altars;

Ezekiel

Ezekiel 28:13

Thou hast been in Eden the garden of God; every precious stone was thy covering, the sardius, topaz, and the diamond, the beryl, the onyx, and the jasper, the sapphire, the emerald, and the carbuncle, and gold: the workmanship of thy tabrets and of thy pipes was prepared in thee in the day that thou wast created.

From Easton's Bible Dictionary

Matthew George Easton, 1897

(1.) A precious gem (Heb. yahalom’, in allusion to its hardness), otherwise unknown, the sixth, i.e., the third in the second row, in the breastplate of the high priest, with the name of Naphtali engraven on it (Ex. 28:18; 39:11; R.V. marg., “sardonyx.”)

(2.) A precious stone (Heb. shamir’, a sharp point) mentioned in Jer. 17:1. From its hardness it was used for cutting and perforating other minerals. It is rendered “adamant” (q.v.) in Ezek. 3:9, Zech. 7:12. It is the hardest and most valuable of precious stones.

From Smith's Bible Dictionary

William Smith, 1884

(Heb. yahalom), a gem crystallized carbon, the most valued and brilliant of precious stones, remarkable for its hardness, the third precious stone in the second row on the breastplate of the high priest, (Exodus 28:18; 39:11) and mentioned by Ezekiel, (Ezekiel 28:13) among the precious stones of the king of Tyre. Some suppose yahalom to be the "emerald." Respecting shamir , which is translated "Diamond" in (Jeremiah 17:1) see under ADAMANT.