Strong’s Greek
G4665 — smaragdos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
σμάραγδος
smaragdos — pronounced smar'-ag-dos
of uncertain derivation; the emerald or green gem so called:--emerald.
1 occurrence in the KJV.
Revelation 21:19
And the foundations of the wall of the city were garnished with all manner of precious stones. The first foundation was jasper; the second, sapphire; the third, a chalcedony; the fourth, an emerald;