Updated as of June 2026
Onyx price and value
What drives Onyx value
The biggest price levers are color saturation and cut, followed by clarity and carat weight. A well cut, vividly colored stone of modest size often beats a larger dull one. Note that onyx is commonly treated (dyeing (most black onyx)), and untreated stones command a premium.
How to buy Onyx without overpaying
Buy from a seller that states treatment and origin, ask for a lab report on higher-value stones, and compare the same carat and color across two or three retailers before committing.
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Frequently asked questions
How much is Onyx per carat?
Onyx generally costs $3 to $40 per carat. Top color and clarity push toward the high end, while included or pale stones sit lower.
Is Onyx a good value?
Onyx can be excellent value when you prioritize color and cut over carat weight. Always compare a certified stone against an uncertified one before deciding.
Why does Onyx price vary so much?
Color saturation, clarity, cut quality, carat weight, origin, and treatment all move the price. Common treatments for this stone: Dyeing (most black onyx).