Onyx

Black stone has long had a place in Southwestern jewelry — historically jet, the fossilized wood-coal worked since ancestral times, and today most often onyx, which offers a similar darkness with greater hardness and availability. As inlay grew more refined, onyx's even color and durability made it a natural choice for the dark passages that frame turquoise, coral, and shell.

Chalcedony of this kind is found worldwide, and the steady supply of consistent black material helped it become a workshop staple in modern Zuni and Navajo inlay.

In Zuni and Navajo inlay, black onyx supplies the dark field, borders, and outlines that give a mosaic its snap, intensifying every color set against it. It is also used on its own in sleek, minimal settings — a single black cabochon in silver — for a contemporary, almost architectural effect. Its hardness lets lapidaries cut precise, sharp-edged pieces that hold a clean line in channel work.

Onyx is a banded variety of chalcedony, the cryptocrystalline form of quartz, and the solid black material used in jewelry takes a deep, glassy polish that wears well in daily use. Most jewelry onyx is color-enhanced to achieve its uniform darkness — a long-standing, stable, and openly accepted practice in the trade rather than a modern shortcut.

At Mohs 6.5 to 7 it is genuinely hard, resisting scratches far better than the softer organic and carbonate stones it is often set beside.