The Sapphire represents the Lord's Divine Nature and His Holy Character as seen in Exodus 24:10, Ezekiel 1:26, 10:1 and Revelation 21:19.
I think it is no coincidence that Sapphire is mentioned 12 times in the bible.
1. Exodus 24:10: "And they saw the God of Israel, and there was under His feet as it were a paved work of sapphire stone, and it was like the very heavens in its clarity." (Moses and the 70 elders)
2. Exodus 28:18: "The second row shall be a turquoise, a sapphire, and a diamond." (On the ephod of Aaron, the High Priest)
3. Exodus 39:11: "The second row, a turquoise, a sapphire, and a diamond." (Same as above)
4. Job 28:5-7: "As for the earth, from it comes bread, but underneath it is turned up as by fire; its stones are the source of sapphires, and it contains gold dust."
5. Job 28:12-16: "But where can wisdom be found? And where is the place of understanding? Man does not know its value, nor is it found in the land of the living. 'The deep says it is not in me'; and the sea says, 'it is not with me.' It cannot be purchased for gold, nor can silver be weighed for its price. It cannot be valued in the gold of Ophir, in precious onyx or sapphire."
6. Song Of Solomon 5:14: "His hands are rods of gold set with beryl. His body is carved with ivory inlaid with sapphires."
7. Isaiah 54:11: "O you afflicted one, tossed with tempest, and not comforted, behold I will lay your stones with colorful gems, and lay our foundations with sapphires."
8. Lamentations 4:7: "Her Nazarites were brighter than snow and whiter than milk; they were more ruddy in body than rubies, like sapphire in their appearance." [Isn't that the same thing as saying "the saints' like in revelation?]
9. Ezekiel 1:26: "And above the firmament over their heads was the likeness of a throne, in appearance like a sapphire stone; on the likeness of the throne was a likeness with the appearance of a man high above it."
10. Ezekiel 10:1: "And I looked, and there in the firmament that was above the head of the cherubim, there appeared something like a sapphire stone, having the appearance of the likeness of a throne."
11. Ezekiel 28:13: "You were in Eden, the garden of God; every precious stone was your covering; the sardius, topaz, and diamond, beryl, onyx, and jasper, sapphire, turquoise, and emerald with gold. The workmanship of your timbrels and pipes was prepared for you on the day you were created."
12. Revelation 21:19: "And the foundations of the wall of the city were adorned with all kinds of precious stones: the first foundation was jasper, the second sapphire, the third chalcedony, the fourth emerald."