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635 B
635 B
Jerusalem
This refers to the "Jerusalem, coming down out of heaven" that he described in the previous verse and not to the physical Jerusalem.
like a very precious jewel, like a stone of crystal-clear jasper
These two phrases mean basically the same thing. The second emphasizes the brilliance of Jerusalem by naming a specific jewel. (See: rc://en/ta/man/translate/figs-parallelism)
crystal-clear
"extremely clear"
jasper
This is a valuable stone. Jasper may have been clear like glass or crystal. See how you translated this in Revelation 4:3. (See: rc://en/ta/man/translate/translate-unknown)