gemstone

Black onyx or black obsidian bead bracelet

Likely chalcedony (microcrystalline quartz, SiO₂) if onyx; alternatively volcanic glass (obsidian)

AI-generated identification · may be incorrect

Glossy black, opaque, rounded polished beads; onyx has Mohs hardness 6.5–7, vitreous/waxy luster, and no cleavage, while obsidian is softer (about 5–5.5) with glassy luster and conchoidal fracture. The image alone cannot distinguish them reliably.

Identified September 7, 2026More gemstone →

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At a glance

Common name: Black onyx or black obsidian bead bracelet
Scientific name: Likely chalcedony (microcrystalline quartz, SiO₂) if onyx; alternatively volcanic glass (obsidian)
Category: gemstone
Identified: September 7, 2026
Method: Standard

AI Estimated Value

Approximately $10–$50 for a common bracelet; $50–$150+ if confirmed high-quality natural onyx with sterling silver or premium workmanship.

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

Black onyx forms by silica deposition in cavities or veins, generally in volcanic or sedimentary settings; obsidian forms when silica-rich lava cools too rapidly to crystallize. These materials range from geologically young volcanic deposits to much older sedimentary-hosted chalcedony.

Uses & applications

Used for jewelry, beads, carvings, and ornamental objects; onyx is more durable for jewelry, while obsidian is valued for its glassy appearance and sharp fracture.

Geological facts

Commercial “black onyx” is often dyed gray, white, or brown chalcedony, and some black beads sold under these names may be glass or synthetic material.

Field identification & locations

Check for natural banding, translucency at thin edges, and uniform dye concentration; glass may show bubbles, and a steel scratch test should not mark true onyx but may mark obsidian. Common sources include Brazil, Uruguay, Mexico, India, and Turkey.