Revelation 4:3

In what sense is God like jasper and sardius (carnelian, NIV) stones? The jasper gem that John saw was evidently a diamond (cf. Revelation 21:11), not what we identify as a jasper today. [Note: Charles, 1:114; Beasley-Murray, p. 113; Mounce, p. 134.] The sardius, named for the town of Sardis where it was discovered, is fiery red. These colored gems probably symbolize the holiness and justice of God (cf. Revelation 1:14; Revelation 10:1; Ezekiel 1:4; Ezekiel 1:26-28; Ezekiel 8:2; Daniel 7:9).

"Perhaps it is better to think of this resemblance as denoting His anger as a reaction of His holy nature in view of the prevailing sinfulness of man and in consequence of which He is about to send judgment upon the earth, that ’the inhabitants of the world will learn righteousness.’" [Note: Smith, A Revelation . . ., p. 103.]

The "rainbow" around the throne was apparently the shape of a rainbow rather than the color of one since this one was green. This bow completely encircled the throne, perhaps resembling a halo. It evidently symbolizes God’s mercy that surrounds His rule (cf. Genesis 9:8-17; Ezekiel 1:28). This rainbow may have been various shades of green suggesting the variegated mercy and grace of God. [Note: Swete, p. 68; Alford, 4:596; Bullinger, p. 217; Homer Hailey, Revelation: An Introduction and Commentary, p. 168.] Another possibility is that the emerald (Gr. smaragd) was a crystal that served as a prism and so yielded a rainbow of colors. [Note: Beasley-Murray, p. 113.]

"Usually, a rainbow appears after the storm; but here, we see it before the storm." [Note: Wiersbe, 2:582.]