Onyx Jewelry

What onyx is

Onyx is a variety of chalcedony, the fine-grained form of quartz. In nature it is banded, often in black and white; sardonyx, an August birthstone, combines layers of reddish sard and onyx. The solid, glossy black that jewelers call black onyx is almost always chalcedony that has been dyed to an even black, a practice that goes back centuries and is standard across the trade. Every onyx in this collection is natural chalcedony, cut mostly as smooth cabochons, flat tablets and shaped hearts and marquises. Our onyx guide covers its history.

Why black onyx works

Black is the ultimate neutral, and onyx gives it depth and polish. Set against white diamonds, it creates a crisp, graphic contrast that suits Art Deco shapes, signet rings and modern geometric designs; in yellow gold it reads bold and classic, in white gold sharp and contemporary. Onyx is also one of the few gems that crosses easily into men's jewelry: our men's signet and cushion rings are among its most traditional uses. For an anniversary, GIA lists onyx for the 7th year.

How to judge onyx

Look for an even, saturated black with no gray patches or visible banding, and a high, glassy polish. Clean edges on a cabochon or tablet matter more than size. Because its color is uniform, onyx lets the design do the talking: an evil eye, an ankh, a claddagh or a starburst of diamonds around a single black stone.

Caring for onyx

Onyx rates about 6.5 to 7 on the Mohs scale, so it handles regular wear with care but scratches more easily than sapphire or diamond. Clean it with warm, soapy water and a soft brush. Keep it away from solvents such as nail polish remover or alcohol, which can affect dyes, and from high heat during repairs; skip ultrasonic and steam cleaners. Store it apart from harder gems. See our Mohs hardness scale and jewelry cleaning guide.

How to choose onyx jewelry

Earrings and pendants are the simplest way to wear onyx every day, from bezel studs to a diamond-halo statement necklace. A black onyx ring makes a strong everyday accent if you take it off for heavy work; signets and cabochon solitaires are the most classic shapes, and the men's rings are cut for a wider hand. Yellow gold gives onyx a warm, vintage richness, while white gold makes the contrast with diamonds sharper. Rings are made to order in your size, so check the sizing guide first.

Onyx Jewelry at a glance