# Onyx

> Onyx is a flat-banded chalcedony, almost always dyed black (6.5-7 on Mohs); a classic of elegant and signet jewelry.

- Source: https://www.711grados.com/en/onyx/
- Language: en
- Note: This entry was drafted with the help of AI and is pending review by the author.
- Published: 2026-08-26
- Updated: 2026-08-26
- Translation (es): https://www.711grados.com/es/onix/
- Author: Sandra Sánchez
- Site: 711 Grados (https://www.711grados.com/)

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Onyx is a chalcedony with straight, parallel bands. The uniform black onyx sold today is usually dyed agate. It pairs very well with gold and silver and is common in signet rings and Art Deco.

## Properties

- **Composition:** silicon dioxide (chalcedony)
- **Hardness:** 6.5 to 7 on the Mohs scale.
- **Color:** black, white and bands; sardonyx is a variety with reddish bands.
- **Origins:** Brazil, India, Uruguay and Mexico.
- **Treatments:** the black is usually dyed.

## Uses in jewelry

- Signet rings and cameos.
- Cabochons and beads.
- Art Deco and mourning jewelry.

## Pros and cons

### Advantages

- Elegant and affordable.
- Resistant to scratches.
- Easy to combine.

### Limitations

- The dye can lose uniformity over time.
- Mistaken for black glass.
- It has no crystalline sparkle.

## Care and cleaning

- Clean with lukewarm water and mild soap.
- Avoid knocks.
- Store apart from harder stones.

## See also

- [Gemstones in jewelry](https://www.711grados.com/en/gemstones-in-jewelry/)
- [Agate](https://www.711grados.com/en/agate/)
- [Quartz and its varieties](https://www.711grados.com/en/quartz/)