Sardonyx

Sardonyx (Greek sardonyx, combining sardion and onyx) is a banded gemstone consisting of layers of sard (reddish-brown chalcedony) and onyx (black or white chalcedony), producing a stone with alternate bands of red/brown and white or black. In classical antiquity it was highly prized for cameo carving, as the contrasting layers allowed craftsmen to carve figures in one layer against a background of another color. It appears in the Bible only in Revelation 21:20 as the fifth of the twelve foundation stones of the new Jerusalem. The precious stones listed in Revelation 21:19–20 collectively evoke the richest materials known to the ancient world, representing the eternal glory and perfection of the city of God. The sardonyx's combination of warm red and bright white also carries symbolic resonance with the blood of Christ and the purity of the saints.