The term translated as “bright” denotes shining, radiance, gleaming. The river’s shine is “as crystal,” a rock that reflects light. Recall from the previous paragraph that the glory of the Lord God gave the city its light, so much so that sun and moon were not needed (Revelation 21:23). This river reflects the shine of God’s radiant glory. That speaks in turn to the source of this river and hence the cause of its potency.
1 Then the angel showed me the river of the water of life, bright as crystal, flowing from the throne of God and of the Lamb