a chalcedony with alternating black and white bands; used in making cameos
"The ancient artisan carefully carved an onyx cameo, revealing its distinctive pattern of alternating black and white bands."
A banded variety of chalcedony, a cryptocrystalline form of quartz.
"The jeweler selected a polished onyx stone to showcase its distinctive dark bands within the white chalcedony matrix."
In plain English: Onyx is a hard, dark stone that people often cut into jewelry because of its shiny black appearance.
"She wore an elegant onyx ring to her anniversary party."
Usage: Do not confuse this gemstone with the black stone used in jewelry; while both are dark varieties of chalcedony, "onyx" specifically refers to the banded type. In casual conversation about watches or rings, it is often mistaken for obsidian due to its similar deep coloration.
jet-black
"The cat's eyes glowed like onyx in the dark room."
A census-designated place in Kern County, California, United States.
"Residents of Onyx gather at the local park to celebrate Independence Day in their small community within Kern County."
The word "onyx" entered English around the year 1300 via Middle English and Old French borrowings from Latin. It ultimately traces back to an Ancient Greek term meaning claw or nail.