Updated as of June 2026
Agate vs Onyx
| Agate | Onyx | |
|---|---|---|
| Price / carat | $2 to $30 | $3 to $40 |
| Hardness (Mohs) | 6.75 | 6.75 |
| Color | Multicolor, Gray, Blue, Brown, White | Black, White, Banded |
| Treatment | Dyeing (very common) | Dyeing (most black onyx) |
The bottom line
Agate and Onyx both make beautiful jewelry. Choose by the look you want first, then weigh hardness against how hard you will wear the piece, and let price settle close calls. Read the full guides for Agate and Onyx.
Frequently asked questions
Is Agate or Onyx more durable?
Both rate Mohs 6.75, so they are comparably durable.
Which is cheaper, Agate or Onyx?
Agate runs about $2 to $30 per carat and Onyx about $3 to $40 per carat, so Agate is usually the more affordable choice.
Which should I choose?
Pick Agate if you want multicolor tones and Onyx if you prefer black. Match the stone hardness to how you will wear it and let budget break the tie.