What is the significance of the emerald rainbow in Revelation 4:3?

Moreover, "One sat on the throne." This glorious Person is not described, but precious stones are used as symbols to set forth His glory. We must remember that God is seen in connection with the throne. It is not the heart of the Father revealed by the Son who dwelt in the Father's bosom that is before us, but the glory of God set forth in Christ on a throne in connection with the government of the universe. The precious stones are symbols setting forth the radiance of divine glory in government. It is seen in heaven though not yet manifest on earth. On earth we see the misgovernment of man and the longsuffering of God. Had the radiancy of the throne manifested itself upon a sinful world it would have involved judgment for all. The vision carries us beyond the day of grace to a time when the church will have been caught up to heaven, to be followed by the radiancy of the throne shining forth in judgment upon the earth.

Further, John sees "a rainbow round about the throne, in sight like to an emerald." From Genesis 9 we know that the rainbow speaks of the everlasting covenant between God and every living creature upon the earth. It speaks of blessing for earth secured by divine promise, but of blessing after judgment. The rainbow comes after the storm, even as God's promise of blessing follows when the judgment of the flood is past. The rainbow encircling the throne is the sure sign that beyond the judgment of the nations will be blessing for the earth.

"He that sat was to look upon like a jasper and a sardine stone." The jasper, as we know, is used as symbolic of the glory of God in connection with the heavenly state. In Rev. 21 it is said, "He carried me away in the Spirit to a great and high mountain, and showed me the holy city, Jerusalem, descending out of heaven from God, having the glory of God: and her light was like unto a stone most precious, even like a jasper stone." I consider therefore that the jasper is used here, and no doubt the sardius also, as symbolic of God's glory, as far as it could be manifested to the creature. There is a glory of God that is entirely above creature contemplation; there is a glory which may become visible to the creature. God has at various times permitted that His glory should shine on men, even on earth; but more so when rapt in the Holy Ghost, into His presence above. At the same time, I say again, it is not, of course, the essential glory of God "to which no man can approach," but as far as God is pleased to make it visible to the creature. It is His glory in government, in the maintenance of good against evil by power.

Round about the throne was seen a rainbow, the sign of God's beneficence to the earth, and at the same time the pledge of a limit put to judgment; but it is not as ordinarily seen among men. (Gen. 9) It recalled that covenant with the earth; but there is no question of rain here, as even in Ezekiel 1:28. It is simply the divine idea. It is not the circumstances of its use or application, but the grand truth that was represented there — the faithful sign of God's covenant with the creature. Hence it was shown in a form which was particularly refreshing to the eye; it was "in sight like unto an emerald."

The complete, unbroken circle round the throne proclaims the truth, “His mercy endureth for ever.” The‎ bow set in the cloud of old, with its prismatic colours and varied beauties, is the token of God’s covenant with the earth (Gen. 9:9-17). It is rarely seen as a complete circle,‎ but generally as an arch, or half-circle, and is God’s object lesson for the race, a public sign hung out in the heavens that all may see and learn that God is good, a lesson from God and of God to men. In the last notice of the rainbow‎ it is seen over the head of the Lord when in power He asserts His claim to the earth. He will sweep the defiled scene with the besom of destruction, but even then the old appointed token of divine goodness reappears ‎(Rev. 10:1). Instead of the combination of‎ colours to which we are accustomed in the rainbow the heavenly one over the throne is “like in appearance to an emerald.” The beautiful green, the characteristic‎ colour of the vegetable world, and the only one which never tires the eye, is the chosen colour of the rainbow beheld by the Seer. The glorified saints will have constantly before their never-tiring gaze the rainbow in its entirety; the remembrance of God’s grace to the earth even when He is about to deal with the race in judgment.‎

"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." (vv. 2, 3.) This is God seated on the throne. The jasper is called "a stone most precious" (Rev. 21:11), and the idea suggested by both gems is that of dazzling glory. It is a session of judgment; for "out of the throne proceeded lightnings, and thunderings, and voices." (v. 5.) Still it is encircled with a rainbow, the token of God's "everlasting covenant" with creation. (Gen. 9:16.) When Ezekiel beheld God about to give up Jerusalem to desolation, he saw "the appearance of the bow that is in the cloud in the day of rain." (Ezek. 1:28.) So here, again, God shows that in judgment He remembers the covenant He has made with the earth. The emerald may be emblematic of the preciousness of the covenant in His sight, or its greenness may indicate the refreshing rest brought to the eye when wearied with the vision of the impending judgments.

We also see a rainbow about the throne. All of its divided colors speak of distinct beauties and glories of the God of creation. Yet it is said to look like an emerald which is green. This is the central color of the spectrum and speaks of the fruitful, refreshing principle of the grace of God. It is wonderful to be assured of this before God's awesome work of judgment must begin (Isa. 28:21). It is His great pleasure to do the work of pure grace as He has done in the salvation of countless numbers through the value of the sacrifice of His beloved Son. Judgment is His extraordinary or “unusual” work, that in which He has no pleasure, though it is a necessary work.

Here, then, is the "appearance" of the One who sits upon the throne; and suitedly the next thing that we read is that about this throne there was "a rainbow, in appearance like unto an emerald." Here, again, we are reminded of the ruin of humanity — reminded, in fact, of the Flood, after which God used the bow as a token that it should recur upon the earth no more — this by His grace alone; and here the bow is but the glory of the light displayed in that which was the storm of judgment, but which is now destined but to refresh and fertilize the earth. It is a promise for the earth that we rightly read in it. Judgment is about to be poured out, but it is a judgment, not to destroy the earth, but to destroy those that would destroy it — a judgment to salvation; and here the character of what is coming before us is shown at once. Israel on the earth is necessarily connected with it, for with blessing for the earth, as we have already seen, the blessing of Israel is an ordained necessity. This is what all the power of the throne is set in motion to accomplish now.

John's first vision in heaven is the established throne, the sign and symbol of the universal government of God. While thrones on earth begin to totter and to fall and man's day closes in the predicted upheavals, there is a throne which cannot be affected or disturbed. Yea, He who sitteth there and looks down upon earth and sees man's rebellion and madness laughs at them and holds them in derision (Psalm 2:4). The occupant of the throne was to look upon like a jasper (rather the diamond) and a sardine stone. Our Lord and the glory of His person are symbolically represented in these stones. His glory in the brilliant stone, His redemption work in the blood-red sardine. The rainbow in emerald-green tells us that in the judgment about to come upon the earth mercy will also be remembered. It is the covenant sign. Though judgments come, yet mercy is in store for Israel and the earth.

*Both are also found in the twelve foundations of the heavenly city; but here the jasper comes first (the glory being at the beginning, so to speak, instead of at the end, as in Judaism) and the sardius the sixth.

The next feature is the rainbow round about the throne, in sight like an emerald. How gracious of God to remind His servant, just as He is about to unfold the long series of judgments wherewith He will smite the earth, of His everlasting covenant with this creation! (Gen. 9) In the midst of His wrath He will remember mercy. This rainbow too is in appearance like unto an emerald, significant, it may be, of the fact that the issue of all God's dealings with the world will be seen in the eternal freshness and beauty of that new earth, together with the new heavens, of which John speaks in Rev. 21.

The "rainbow round about the throne," bright and beautiful, "in sight like unto an emerald," tells us that the throne is set in relation to earth, and that He who set His bow in the cloud, as the token of the covenant that He would never again destroy the earth with water, is the faithful covenant-keeping God.

But, besides the appearance of divine glory, there was a rainbow round about the throne. This evidently carries our thoughts back to the covenant that God made, not with His people Israel, but with the earth at large. The covenant with His people is noticed for the first time in Revelation 11, where we have heaven opened and the ark of His testament seen in His temple. It is not the new covenant itself; for when this is brought about, there will be no earthquakes, and lightnings, and thunders, etc., but the day of peace and blessing for Israel. But at the time to which that vision refers, God will show that He has respect to His covenant. Here the rainbow is God's remembrance of His covenant with the earth. The ark spoken of in Revelation 11 is God's remembrance of His covenant with His people. God is going to pour forth judgments on the earth and on those who had the responsibility of being His people. But He takes pains to show that, before a single judgment falls, there is mercy in store. Before He touches creation, there is the sign of His covenant with the earth, just as when He is forced to pour down plagues on His people Israel, the ark of His covenant is seen. The rainbow was the witness that God had not let slip His ancient word: He could not forget it. The rainbow is the sign of mercy. It spans the heavens, and takes in earth and sea, the whole compass of that blessed security of which God had hung out the token on high. And now we have the rainbow not merely over the world, but round about the throne in heaven. This is not its usual place; but it was comforting for John to see, in the midst of all that bright glory, how God wished to fill the heart with confidence. He had not merely the vision of what was coming on earth, but in the circle of the divine manifestation and power the rainbow is seen above. If God shows us His own glory at the same time, the rainbow would tell us that God is true — that He was purposely putting man in mind of His pledge, given after the great judgment of old, and the rather as now He set it in this peculiar place, where a rainbow had never been seen before, in order to assure our hearts. But though peculiar, what could be more in character? For it is the throne of God the Almighty, the Creator and supreme Lord of all things.