gemstone

Black polished gemstone bead, likely obsidian or black onyx

Obsidian: volcanic glass (mainly SiO₂); black onyx: microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Smooth, spherical, highly polished, opaque black with vitreous luster; obsidian has hardness ~5–5.5 and conchoidal fracture, while onyx is harder at ~6.5–7. Crystal structure is absent in obsidian and cryptocrystalline in onyx.

Identified August 31, 2026More gemstone →

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At a glance

Common name: Black polished gemstone bead, likely obsidian or black onyx
Scientific name: Obsidian: volcanic glass (mainly SiO₂); black onyx: microcrystalline quartz (SiO₂)
Category: gemstone
Identified: August 31, 2026
Method: Standard

AI Estimated Value

Approximately $2–$20 for a common polished bead; unusual natural material or fine jewelry settings may be worth $25–$100+.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Obsidian forms when silica-rich lava cools rapidly, commonly during the Quaternary and older volcanic episodes; black onyx forms as chalcedony deposited in layered cavities. The image alone cannot distinguish them reliably.

Uses & applications

Used for beads, cabochons, carvings, jewelry, and ornamental objects; obsidian also has historical toolmaking significance.

Geological facts

A strong light may reveal translucence at thin edges in obsidian or subtle banding in onyx. Perfect spherical shaping and drilling indicate human processing.

Field identification & locations

Likely identified by its glassy luster and conchoidal fracture if obsidian, or waxy luster and very fine banding if onyx. Common sources include Mexico, the western United States, Brazil, India, and Uruguay.