Crystal

“Neither gold nor crystal can compare to it, nor jewels of fine gold be exchanged for it.”

“Spread out above the heads of the living creatures was the likeness of an awesome expanse, gleaming like crystal.”

“And before the throne was something like a sea of glass, as clear as crystal. In the center, around the throne, were four living creatures, covered with eyes in front and back.”

“shining with the glory of God. Its radiance was like a most precious jewel, like a jasper, as clear as crystal.”

“Then the angel showed me a river of the water of life, as clear as crystal, flowing from the throne of God and of the Lamb”