And the foundations of the wall of the city were adorned with all manner of precious stones. The first foundation was jasper: the second, sapphire: the third, a chalcedony: the fourth, an emerald:
Clement of Alexandria
Tradition assures us that the heavenly Jerusalem that is above is built up of holy gems, and we know that the twelve gates of the heavenly city, which signify the wonderful beauty of the apostolic teaching, are compared with precious jewels. These priceless stones are described as possessing certain colors that are themselves precious, while the rest is left of an earthly substance. To say that the city of the saints is built of such jewels, even though it is a spiritual edifice, is a cogent symbol indeed. By the incomparable brilliance of the gems is understood the spotless and holy brilliance of the substance of the spirit.
Imported from an open dataset — not yet checked against the printed edition.