There are two things in Ezekiel's vision that corresponds with John's vision of the 'Throne of God.' :

           First, that the form of the one who sat on
                    the Throne could not be clearly
                    recognized or described, but that it
                    was surrounded with Light, which
                    veiled the form or person; and
      Second, that there was a Rainbow round
                    about the Throne.
                   The person of God then, as He sits
                   upon His Throne, is veiled in a Glory
                   that can only be compared to the
                   shining of a gem.

One of the remarkable things about the Throne of God is, that it is surrounded by a 'Rainbow' that is emerald in color.