Revelation 4:6
And there was an ocean, as crystal-clear as glass, in front of the throne. And at the center, surrounding the throne were four living beings, covered with eyes in the front and back of them. [Note: In view of Isa. 6:1-3 and especially Eze. 10:20ff, these "living beings" appear to be some special order of heavenly beings who inhabit the presence of God].
Revelation 4:3
And He who was seated [on it] appeared like jasper [i.e., possibly diamond. See 21:11] and carnelian [i.e., possibly a brilliant red stone], and there was a rainbow, resembling an emerald, surrounding the throne.
Revelation 21:11
It had the splendor of God [shining from it], and was as brilliant as a very precious stone, as crystal-clear as jasper.