Five of our ten comparison translations, used in this series, render the word sappiyr as "sapphires," with three others (ESV, HCSB and NIV) stating the stone could also be a lapis lazuli. The NASB translates the word directly as "lapis lazuli" while the NLT renders it "blue lapis lazuli."
Even though this gem is likely one of those that adorned Lucifer before he became the devil, the middle stone in the second row of the High Priest's breastplate likely is not. Please see our article on lapis lazuli in the Bible for more information.
The Greek word sappheiros (Strong's #G4552) is used for sapphires composing the second foundation in the New Jerusalem to be built by God (Revelation 21:19). In modern times, these precious gems are not only used in jewelry but also for scientific instruments, impact resistant windows and the inner workings of wristwatches.
Sapphires, in ancient times, were believed not only to be an antidote against poison but also a powerful charm that protected the wearer from fever (Diamonds, Pearls and Precious Stones, page 60).
This gemstone was also believed to protect kings from harm. Those who wore the gemstone also did so because it was thought not only to protect them from envy but also to grant them favor with God.
Those who were necromancers (who used black magic to trick others they were contacting the dead) highly valued sapphires for its believed power to enable them to hear and understand obscure oracles (Curious Lore of Precious Stones, page 104 - 105).