We might be inclined to research the stone known to gemologists as “jasper” for a sense of John’s comparison. But that is hardly helpful, not the least because it is difficult to determine whether John meant by the term what today’s gemologists understand by “jasper.” It is far more helpful to recall that John used the same term (“jasper”) in his effort to describe the One who sat on the throne of heaven (Revelation 4:3). So the term underscores the opening words of Revelation 21:11, that is, that the Bride has the glory of God. The additional “clear as crystal” communicates the total absence of impurities (aggregates) in this jasper, to the point of being translucent, which again speaks to the divine splendour of her beauty (Revelation 19:8).
11 having the glory of God, its radiance like a most rare jewel, like a jasper, clear as crystal.