18 The wall was made of jasper, and the city of pure gold, as pure as glass.
19 The foundations of the city walls were decorated with every kind of precious stone. The first foundation was jasper, the second sapphire, the third chalcedony, the fourth emerald,
20 the fifth sardonyx, the sixth carnelian, the seventh chrysolite, the eighth beryl, the ninth topaz, the tenth chrysoprase, the eleventh jacinth, and the twelfth amethyst.
21 The twelve gates were twelve pearls, each gate made of a single pearl. The great street of the city was of pure gold, like transparent glass.
Revelation 21:18-21
It is hard to imagine, but much more is revealed for us in the book of Revelation:
1 Then I saw a new heaven and a new earth; for the first heaven and the first earth passed away, and there is no longer any sea.
2 And I saw the holy city, new Jerusalem, coming down out of heaven from God, made ready as a bride adorned for her husband.
3 And I heard a loud voice from the throne, saying, "Behold, the tabernacle of God is among men, and He will dwell among them, and they shall be His people, and God Himself will be among them,
4 and He will wipe away every tear from their eyes; and there will no longer be any death;
there will no longer be any mourning, or crying, or pain; the first things have passed away."
5 And He who sits on the throne said, "Behold, I am making all things new."
And He said, "Write, for these words are faithful and true."
6 Then He said to me, "It is done. I am the Alpha and the Omega, the beginning and the end.
I will give to the one who thirsts from the spring of the water of life without cost.
Revelation 21:1-6