#5306 נֹפֶךְ nophek {no'-fek}

 from an unused root meaning to glisten; TWOT - 1391; n m

—Hebrew Word Study (Transliteration-Pronunciation Etymology & Grammar)

 1) a precious stone in the high priest's breastplate
    1a) perhaps an emerald, turquoise, ruby, or carbuncle
 2) jewels imported from Tyre

—Brown-Driver-Briggs (Old Testament Hebrew-English Lexicon)

—Strong's (Hebrew & Chaldee Dictionary of the Old Testament)

—NAS Exhaustive Concordance of the Bible with Hebrew-Aramaic and Greek Dictionaries

 AV - emerald 4; 4

—Exhaustive Concordance (KJV Translation Frequency & Location)