Updated as of June 2026
Onyx
A sleek black chalcedony traditionally worn for grounding, strength, and protection against negativity.
Price range$3 to $40/ct
Hardness (Mohs)6.75
ColorsBlack, White, Banded
BirthstoneNone
AltGems Score How we score
5.4/10
Onyx pros and cons
Pros
- Good durability (Mohs 6.75) for most jewelry
- Strong value for the look
Cons
- Softer at Mohs 6.75, best in protected settings
- Commonly treated (dyeing (most black onyx))
- Opaque, so it shows color rather than sparkle
Onyx is ideal for earrings, pendants, and occasional-wear rings, and works in everyday rings with a protective setting.
Explore Onyx
Meaning and properties
Symbolism, zodiac, chakraPrice and value
What it costs and whyBuying guide
How to choose and where to buyCare and cleaning
Keep it looking its bestOnyx jewelry
Common buying mistakes
- Buying on carat weight alone instead of color and cut, which drive beauty more.
- Skipping treatment disclosure, which changes both value and care.
- Setting this softer stone (Mohs 6.75) in an exposed daily-wear ring instead of a protective bezel or halo.
- Cleaning it the wrong way. Durable. Clean with warm soapy water and a soft cloth. Avoid harsh chemicals and prolonged heat.
You may also like
Where to buy Onyx: for fine pieces, choose established jewelers with clear return policies and lab reports; for unique or budget pieces, vetted marketplace sellers work well. Always confirm treatment and the return window before buying. AltGems prices are general per-carat guides, so verify value with a certified gemologist or GIA report.
Frequently asked questions
What is Onyx?
A sleek black chalcedony traditionally worn for grounding, strength, and protection against negativity. It rates 6.75 on the Mohs hardness scale and commonly appears in black, white, banded.
How much does Onyx cost?
Onyx typically runs about $3 to $40 per carat depending on color, clarity, cut, and origin. See our Onyx price guide for detail.
Is Onyx good for everyday jewelry?
It rates 6.75 on the Mohs scale, so it suits earrings, pendants, and occasional-wear rings better than daily rough use.
What is the AltGems Score for Onyx?
Onyx earns an overall AltGems Score of 5.4 out of 10, balancing durability, brilliance, value, rarity, and everyday wearability. See our methodology on the How We Score page.
How do I care for Onyx?
Durable. Clean with warm soapy water and a soft cloth. Avoid harsh chemicals and prolonged heat.