Abarim Publications' online Biblical Hebrew Dictionary
ספיר
The masculine noun ספיר (sappir), usually translated with sapphire, was imported along with the stone, from the Afghanistan-Iran region, and derives from the Sanskrit word canipriya. Still, it appears that the various words derived from canipriya covered more than just the blue gem we now know as sapphire. Most scholars indicate that often lapis lazuli or lazurite was meant.
In Exodus 24:10, Moses, Aaron, Nadab and Abihu and the seventy elders of Israel see God standing on a sapphire-like pavement, as clear as the sky, and Ezekiel, likewise, sees an expanse like a throne made from sapphire over the heads of the cherubim (Ezekiel 1:26 and 10:1).
John the Revelator sees the sapphire among the foundation gem stones of the city wall of the New Jerusalem (Revelation 21:19), and the prophet Isaiah sees the foundations of the Wife of God laid in with sapphires (Isaiah 54:11).
Solomon takes the idea of a sapphire inlaid foundation even further. The bride of the Song of Solomon reviews the physique of her husband to be, and swoons over his abs, which to her looks like carved ivory laid in with sapphires (Song of Solomon 5:14). Jeremiah applies sapphire to whole bodies as he laments the polished-like-sapphire appearance of the Nazirites of Zion before the war with Babylon wrecked them (Lamentations 4:7).
In a lament over the "king of Tyre" (literally: the king of the rock) Ezekiel sees the sapphire among the gems in Eden (Ezekiel 28:13), and these paradisiacal stones were utilized to form the front-piece of the apparel of the high priest (Exodus 28:18). Of the twelve gems in the breast plate of the high priest, the sapphire was the middle one of the second row from the top. That makes it the top gem of the two central ones.
Still, the sapphire was by far not the most desirable commodity. While Job wonders where wisdom may be found, he lists the sources of various precious metals and stones, and reports that sapphires come from rocks (Job 28:6). He also submits that wisdom can never be paid for in silver, gold or sapphires (Job 28:16).