(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.