Spread out above the heads of the living creatures was what looked something like a vault, sparkling like crystal, and awesome.
NIV
Over the head of the [combined] living creature there was the likeness of a firmament, looking like the terrible and awesome [dazzling of shining] crystal or ice stretched across the expanse of sky over their heads.
AMP
And the likeness of the firmament upon the heads of the living creature was as the colour of the terrible crystal, stretched forth over their heads above.
KJV
Also before the throne there was what looked like a sea of glass, clear as crystal. In the center, around the throne, were four living creatures, and they were covered with eyes, in front and in back.
NIV
And in front of the throne there was also what looked like a transparent glassy sea, as if of crystal. And around the throne, in the center at each side of the throne, were four living creatures (beings) who were full of eyes in front and behind [with intelligence as to what is before and at the rear of them]. [Ezek. 1:5, 18.]AMP
And before the throne there was a sea of glass like unto crystal: and in the midst of the throne, and round about the throne, were four beasts full of eyes before and behind.
KJV
It shone with the glory of God, and its brilliance was like that of a very precious jewel, like a jasper, clear as crystal.
NIV
Clothed in God's glory [in all its splendor and radiance]. The luster of it resembled a rare and most precious jewel, like jasper, shining clear as crystal.
AMP
Having the glory of God: and her light was like unto a stone most precious, even like a jasper stone, clear as crystal;
KJV