Jasper: see verse 11 and 4.3.

The city was pure gold: this includes the streets and the buildings. One may also say “everything in the city was made out of pure gold.”

Clear as glass: this seems to indicate very pure gold, of the highest quality. The light of the city seems to shine through the gold (clear as glass). An alternative model for this final sentence is “Everything in the city was made out of gold, so pure that light seemed to shine through it just like glass.”

Quoted with permission from Bratcher, Robert G. and Hatton, Howard A. A Handbook on The Revelation to John. (UBS Handbook Series). New York: UBS, 1993. For this and other handbooks for translators see here .