Albert Barnes Commentary Revelation 21:21

"And the twelve gates were twelve pearls; each one of the several gates was of one pearl: and the street of the city was pure gold, as it were transparent glass." — Revelation 21:21 (ASV)

And the twelve gates. Revelation 21:12.

Were twelve pearls. See Barnes on Revelation 17:4; Matthew 13:46.

Every several gate was of one pearl. Each gate. Of course, this is not to be understood literally. The idea is that of ornament and beauty, and nothing could give a more striking view of the magnificence of the future abode of the saints.

And the street of the city was pure gold. Was paved with gold; that is, all the vacant space that was not occupied with buildings was of pure gold. See Barnes on Revelation 21:18.