“And the building of the wall of it was of jasper: and the city was pure gold, like unto clear glass.”
King James Version (KJV)
21:18 And the building of the wall was jasper - That is, the wall was built of jasper. And the city - The houses, was of pure gold.
Re 21:18 And the building of the wall of it was [of] jasper. A brightly radiant stone. See Re 21:11. And the city [was] pure gold, like unto clear glass. The symbols indicate that the city is beautiful and rich beyond conception. The costliest materials known to mortals are named in order to give us some idea.