'Diamond' in the Bible

The sin of Judah is engraved with an iron stylus. It is inscribed with a diamond point on the tablet of their heart and on the horns of their altars.

I'm making you harder than flint like diamond! So you are not to fear them or be intimidated by how they look at you, since they're a rebellious group."

You used to be in Eden God's paradise! You wore precious stones for clothing: ruby, topaz, diamond, beryl, onyx, jasper, sapphire, turquoise, and carbuncle. Your settings were crafted in gold, along with your engravings. On the day of your creation they had been prepared!

They made their hearts hard like a diamond, to keep from obeying the Law and the messages that the LORD of the Heavenly Armies sent by his Spirit through the former prophets.