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. And he that sat - There is here no description of the Divine Being, so as to point out any similitude, shape, or dimensions. The description rather aims to point out the surrounding glory and effulgence than the person of the almighty King. See a similar description Numbers 24:10, etc., and the notes there.
Related Commentaries of Revelation 4:3
Revelation 4:3
3 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.