When God appeared unto Noah after the flood, and placed a rainbow in the sky; he did much more than show him a phenomenon. In the seven colours of the rainbow, beginning with red and ending with purple, God was displaying a natural miracle that demonstrated the complete redemption and salvation of man.
First let us look at colour in the natural world. In the world of art, we have three primaries; red, yellow and blue. These cannot be formulated by mixing. They come from the earth; but with these three colours, and the addition of black and white, any shade of the spectrum can be obtained.
But where did these primary colours come from? God was showing himself with colour and man never knew it.
Gold/Yellow when used anywhere in scripture show to be a symbol of wealth power and authority just like G-d the Father; and Blue is a colour found in the prayer shawls representing the sky and the wind ans in the rushing mighty wind all bointing to God the Spirit, and then there is the colour red. red in hebrew is (adam) red is the colour of blood it constantly in scripture deals with atonement and sacrifices thus it stands for God the Son.
In this fact alone lies a thought provoking, scriptural principle!
White, the Shakanah Glory, is the colour that is comprised of all the colours of the spectrum. Refraction of white light produces the rainbow colours which consist of red, orange, yellow, green, blue, indigo (purple), violet. Other colours consist of the infrared and Ultraviolet spectrum Infrared and Ultraviolet represent that which is unseen.
The rainbow represents the promises of God and was a sign of the covenant that God would never again flood the earth with water: "I set My rainbow in the cloud, and it shall be for the sign of the covenant between Me and the earth... .. the waters shall never again become a flood to destroy all flesh." Gen 9:13,15
The rainbow signifies the glory, majesty and honour of the Lord Jesus Christ "One sat on the throne. And He who sat there was like a jasper and a sardius stone in appearance; and there was a rainbow around the throne, in appearance like an emerald." (Rev 4:2-3)