gemstone

Faceted blue-violet gemstone, likely iolite or blue topaz

Likely cordierite (iolite), Mg2Al4Si5O18; alternative: topaz, Al2SiO4(F,OH)2

AI-generated identification · may be incorrect

Small transparent-to-translucent, faceted blue-violet stone with vitreous luster and strong color variation; iolite has Mohs hardness 7–7.5, while topaz is 8. Crystal structure is orthorhombic (iolite) or orthorhombic (topaz), with imperfect cleavage.

Identified August 26, 2026More gemstone →

Explore Faceted blue-violet gemstone, likely iolite or blue topaz 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: Faceted blue-violet gemstone, likely iolite or blue topaz
Scientific name: Likely cordierite (iolite), Mg2Al4Si5O18; alternative: topaz, Al2SiO4(F,OH)2
Category: gemstone
Identified: August 26, 2026
Method: Standard

AI Estimated Value

Approximately $10–$100 for a small common faceted stone; fine natural iolite may reach $100–$300, while confirmed quality blue topaz commonly sells for $20–$200.

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

These are natural mineral crystals formed in igneous rocks: iolite commonly crystallizes in silica-rich metamorphic or plutonic environments, whereas topaz forms in granite pegmatites and hydrothermal cavities. Ages vary widely, commonly millions to billions of years.

Uses & applications

Used primarily as a collector or jewelry gemstone; topaz is more durable for rings, while iolite is often used in pendants and earrings. Value depends strongly on clarity, color, cut, and confirmed identity.

Geological facts

Iolite is strongly pleochroic, appearing blue, violet, gray, or nearly colorless when viewed in different directions; this historically earned it the name “water sapphire.” The image alone cannot reliably distinguish iolite from blue topaz or treated sapphire.

Field identification & locations

Confirm identity with refractive index, specific gravity, dichroscope, and hardness testing; do not scratch the stone casually. Iolite occurs in India, Sri Lanka, Madagascar, Brazil, and Norway; blue topaz is common in Brazil and often irradiated and heat-treated.