'Diamond' in the Bible

I have made your forehead like a diamond, harder than flint. Don’t be afraid of them or discouraged by the look on their faces, even though they are a rebellious house.”

Thou hast been in Eden the garden of God; every precious stone was thy covering, the sardius, topaz, and the diamond, the beryl, the onyx, and the jasper, the sapphire, the emerald, and the carbuncle, and gold: the workmanship of thy tabrets and of thy pipes was prepared in thee in the day that thou wast created.