Onyx is a semi-precious stone with distinctive bands of color, most commonly seen in black and white stripes. These bands form in layers, like the rings inside a tree trunk, creating striking patterns that have fascinated people for thousands of years.

Ancient civilizations prized onyx for carving cameos and seals. A cameo is a small carved portrait or design where an artist skillfully cuts into the stone's layers, using the contrasting colors to make the image stand out. Roman emperors wore onyx signet rings to stamp their personal seals into wax on important documents.

Today, jewelers still use onyx in rings, necklaces, and bracelets, particularly the pure black variety. The stone's smooth surface takes a beautiful polish, making it shine like dark glass. Architects sometimes use onyx in thin slabs for decorative walls and countertops because light can pass through it, creating a warm glow.

You might hear someone describe something as “black as onyx” when they want to emphasize how deeply dark it is.