The New Jerusalem is described In Revelation chapter 21. "And he carried me away...and showed me the Holy City, Jerusalem, coming down out of heaven from God." (21:10). The physical description is that of a very large space station. It is a cube, measuring approximately 1500 miles long, 1500 miles wide, and 1500 miles high. To give some idea of what those dimensions mean: the whole surface of the earth could be replicated in approximately 100 stories, each story being about 15 miles high!
Glass and jasper are mentioned in several places. Both are silicates (the principle component of sand), which is found in abundance. Silicate building materials have been developed that are stronger per pound than steel. Light shining through, or refracted by, the material makes the material look like precious stones (with the color and intensity dependent upon small amounts of other elements embedded in the silicates).
The 12 gates of pearl, could be spherical air locks. Gold, and/or a transparent material that looks like gold, maybe used in the streets (for utilities?). Today we are well aware of electric lighting, so it is easy to visualize a city that: "...does not need the sun or the moon to shine on it..."