gemstone

Black faceted gemstone, likely spinel or black tourmaline

Most plausibly black spinel (MgAl₂O₄); visually similar possibilities include schorl tourmaline (NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄) or synthetic glass

AI-generated identification · may be incorrect

Small, dark blue-black, transparent-to-opaque faceted stone with vitreous luster and conchoidal-looking reflections. Spinel is cubic, lacks cleavage, has Mohs hardness 7.5–8 and specific gravity about 3.6; the photograph cannot confirm identity.

Identified September 7, 2026More gemstone →

Explore Black faceted gemstone, likely spinel or black tourmaline in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Black faceted gemstone, likely spinel or black tourmaline
Scientific name: Most plausibly black spinel (MgAl₂O₄); visually similar possibilities include schorl tourmaline (NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄) or synthetic glass
Category: gemstone
Identified: September 7, 2026
Method: Standard

AI Estimated Value

About $2–$20 if a small commercial black bead or synthetic stone; roughly $20–$150+ if confirmed natural, well-cut black spinel, depending on size and quality.

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

Natural spinel crystallizes in metamorphic limestones and some igneous rocks, commonly forming during regional metamorphism; gem deposits range from ancient to relatively young. Schorl forms in boron-rich granitic pegmatites and hydrothermal veins.

Uses & applications

Used as a jewelry stone when natural and sufficiently transparent; black spinel is also sold as an inexpensive bead or faceted accent. Tourmaline is collected and occasionally used in jewelry and scientific/electrical applications.

Geological facts

The strong geometric reflections indicate faceting rather than a typical rough mineral crystal. Color alone is unreliable because black spinel, tourmaline, corundum, obsidian, and synthetic materials can appear similar.

Field identification & locations

Check hardness, specific gravity, refractive index, and inclusions; a jeweler’s refractometer or gemological lab is recommended. Spinel commonly occurs in Myanmar, Sri Lanka, Tanzania, Vietnam, and Tajikistan; black tourmaline is widespread worldwide.