Heb. nophek ( Exodus 28:18 ; 39:11 ); i.e., the "glowing stone", probably the carbuncle, a precious stone in the breastplate of the high priest. It is mentioned ( Revelation 21:19 ) as one of the foundations of the New Jerusalem. The name given to this stone in the New Testament Greek is smaragdos, which means "live coal."
M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition,
published by Thomas Nelson, 1897. Public Domain, copy freely.
[N] indicates this entry was also found in Nave's Topical Bible
[S] indicates this entry was also found in Smith's Bible Dictionary
Bibliography InformationEaston, Matthew George. "Entry for Emerald". "Easton's Bible Dictionary".