A market-wide average across qualities and sizes. Your stone's value depends on carat, color, clarity, cut, treatment, and origin.
Opal is a hydrous silica (SiO₂·nH₂O) that can occur as precious opal—showing play-of-color—or as common opal without this effect. Precious opal includes white, crystal, black, boulder and matrix opal types, while fire opal refers to bodycolor (typically orange to red) with or without play-of-color. With Mohs hardness around 5.5–6.5 and relatively low toughness due to its hydrated, amorphous structure, opal requires protective settings and care to avoid cracking or crazing.
Market averages will not price your stone. GemstoneAI identifies gems and jewelry from a photo, checks authenticity and treatment signals, and gives you a real market valuation in seconds. Free to try.
The GemstoneAI market index for opal is $194 per carat as of 2026-08-04. That is a market-wide average across qualities, not a quote for a specific stone. Individual value depends on carat, color, clarity, cut, treatment, and origin.
Visual tests alone are unreliable. GemstoneAI analyzes a photo of your stone for identity, treatment indicators, and authenticity signals, then estimates market value. It is free to try.
Over the past 30 days the opal index moved -8.6%. Gem prices move on supply, demand, and metal markets; treat any single stone as a collectible first and an asset second.