The passage in Revelation xxi, 19, 20, is not the only one in that book treating of precious stones, for we read in chapter iv, 2, 3:
And immediately I was in the Spirit: and, behold, a throne was set in heaven, and one sat on the throne.
And he that sat was to look upon like a jasper and a sardine stone: and there was a rainbow round about the throne, in sight like unto an emerald.
The commentators, both ancient and modern, have given many different explanations of the symbolic meaning of the similes employed here. Some have seen in the two stones a type of the two judgments of the world, by fire and by water; others find that they signify the holiness of God and his justice. Of the rainbow “like unto an emerald,” Alford says we should not think it strange that the bow is green, instead of prismatic: “the form is that of the covenant bow, the color even more refreshing and more directly symbolizing grace and mercy.”[424]
The significance of the twelve Apocalyptic gems is given by Rabanus Maurus, Archbishop of Mainz (786-856), in the following words:[425]
In the jasper is figured the truth of faith; in the sapphire, the height of celestial hope; in the chalcedony, the flame of inner charity. In the emerald is expressed the strength of faith in adversity; in the sardonyx, the humility of the saints in spite of their virtues; in the sard, the venerable blood of the martyrs. In the chrysolite, indeed, is shown true spiritual preaching accompanied by miracles; in the beryl, the perfect operation of prophecy; in the topaz, the ardent contemplation of the prophecies. Lastly, in the chrysoprase is demonstrated the work of the blessed martyrs and their reward; in the hyacinth, the celestial rapture of the learned in their high thoughts and their humble descent to human things out of regard for the weak; in the amethyst, the constant thought of the heavenly kingdom in humble souls.
The origin of the foundation stones named in Revelation xxi, 19, 20, may be found in the text, Isaiah liv, 11, 12, where we read:
O thou afflicted, tossed with tempest, and not comforted, behold, I will lay thy stones with fair colours, and lay thy foundations with sapphires.
And I will make thy windows of agates, and thy gates of carbuncles, and all thy borders of pleasant stones.
As we see, only three stones are mentioned by name: the sapphire, the carbuncle, and “agates.” This last rendering is quite doubtful, as the Hebrew word (kodkodim) signifies shining or gleaming stones, and their use for windows indicates that they must have been transparent. It is easy to understand that in later times the twelve stones of the breastplate, dedicated to the twelve tribes of Israel, were used to fill out and complete the picture, following the indication given by the general terms “stones with fair colours” and “pleasant stones.”
In commenting on this text Rabbi Johanan is quoted in the Babylonian Talmud as saying that God would bring jewels and pearls thirty ells square (twenty ells in height and ten in width) and would place them on the gates of Jerusalem. There may be in this some reminiscence of the Apocalyptic foundation stones. A sceptical disciple said to the Rabbi, “We do not ever find a jewel as large as the egg of a dove.” But not long afterward, when this same disciple was sailing in a boat on the sea, he saw angels sawing stones as immense as those described by Rabbi Johanan, and when he asked for what they were designed, the reply was, “The Holy One, blessed be He, will place them on the gates of Jerusalem.”[426]