21:18And the material of the wall was jasper; and the city was pure gold, like clear glass.

And the MATERIAL of the WALL was jasper;

That the New Jerusalem exists and has substance is given by the expression "the MATERIAL of the WALL". Yet, imagine the difficulty this presented to John when he was shown what the GLORY of GOD looked like (verse 11). John is consistent with his previous description of the One who sits upon the THRONE (Revelation 4:3). None of us, neither the readers nor this author, has experienced our transformed body, so we have a difficult time 'seeing' what our true and pure spiritual nature is (Philippians 3:17-21).

Jasper was a revered gem in ancient times. It is mostly unknown to us in modern times. It is clear, however, that jasper represents the righteousness and purity of God. Given that all of us are living with a sin besmirched mind, we cannot possibly understand this purity (1 Corinthians 13:1-12-13).

and the CITY was PURE GOLD, like clear glass.

The CITY is, in fact, the one that the angel is showing John (verses 9 - 11) and is the BRIDE of Jesus Christ. PURE GOLD is a way to show the purity and blamelessness of the inhabitants of the CITY (Ephesians 5:22-27-33). Furthermore, GOLD is aligned with both deity and royalty as of a kingdom. We are told that we are a kingdom in Revelation 1:6.

The CITY is like clear glass meaning that it is totally transparent or in a different way of looking at it, the glory of God (verse 11) shows through and throughout the CITY. There is no privacy in the new Jerusalem, There is no need for it. For that matter, even today you and I are totally transparent to Jesus (Hebrews 4:12-13). I don't know about you, but sometimes I wish it were different. However, I sure am glad that Jesus constantly forgives my "iniquities" in order to get me ready for this transparent new Jerusalem!