21:11 having the glory of God. Her brilliance was like a very costly stone, as a stone of crystal-clear jasper.

having THE GLORY OF GOD.

John understands what the angel (verse 9) is showing him. During John's old world life, he had seen this happen to Jesus, God's Son while up on a mountain top (Matthew 17:1-2-8). For a moment, Jesus went beyond his old earth appearance into a transformed state, When God is pleased, His GLORY blossoms forth. For example, at the announcement of Jesus' birth to the shepherds (Luke 2:8-9-20), they were frightened by the GLORY of the Lord that surrounded the angels.

HER BRILLIANCE was like a very costly stone, as a stone of crystal-clear JASPER.

The 'HER' here refers back to the Bride (verse 9). And describing HER with the BRILLIANCE attribute shows the equivalency of the Bride with Christ. She truly has become Christ's WIFE (verse 9). We are seeing the glorification of the believers in the new earth/heaven/Jerusalem just as Paul in Romans 8:12-17 says would happen. That we are heirs of God and fellow heirs with Christ becomes visually apparent. However, we are reminded that this came at a 'very costly' price, the price of Christ's death and resurrection, is signified by this stone of crystal-clear JASPER.

A side thought: In physics, BRILLIANCE is associated with a lot of energy. If Einstein's concept that the ratio of energy to mass (matter) is the square of the speed of light (E/m = c2) is true, then the Bride here is a very much transformed body (old earth mass) to a bundle of energy (new Jerusalem BRILLIANCE). Paul describes this in another way in Philippians 3:17-20-21.