“And the twelve gates were twelve pearls; every several gate was of one pearl: and the street of the city was pure gold, as it were transparent glass.”
King James Version (KJV)
Re 21:21 The twelve gates [were] twelve pearls. Each gate composed of a single pearl. The street of the city [was] pure gold. The streets were paved with pure gold. As it were transparent glass. Transparency is the symbol of purity.