Strong’s Greek
G5194 — hualos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ὕαλος
hualos — pronounced hoo'-al-os
perhaps from the same as 5205 (as being transparent like rain); glass:--glass. see GREEK for 5205
2 occurrences in the KJV.
Revelation 21:18
And the building of the wall of it was of jasper: and the city was pure gold, like unto clear glass.
Revelation 21:21
And the twelve gates were twelve pearls: every several gate was of one pearl: and the street of the city was pure gold, as it were transparent glass.