Kyanite
Kyanite
Blue to blue-green; strongly variable hardness along crystal axes
Blue
Blue-Green
Optical characteristics
- Ref. index
- 1.716 – 1.731
- Birefringence
- 0.012 – 0.017
- Luster
- Vitreous
- Pleochroism
- Strong Trichroic: colorless, violet-blue, and blue depending on crystallographic axis.
- Fluorescence
- Typically inert to weak red under LW UV.
Source localities
Tanzania
Tanzania: Merelani Hills
Significant
Sole source of tanzanite worldwide; also produces tsavorite, ruby, sapphire and rare collector gems.
Brazil
Brazil: Minas Gerais / Paraíba / Bahia
Significant
Major source for beryl, tourmaline, quartz, topaz, chrysoberyl and rare minerals.
Kenya
Kenya: Tsavo region
Significant
Classic source for tsavorite and other East African garnets.
Afghanistan
Afghanistan: Panjshir / Nuristan / Badakhshan
Significant
Known for emerald, tourmaline, kunzite, lapis lazuli and rare minerals.
India
India: Rajasthan / Odisha / Karnataka
Significant
Historic and modern source for garnet, moonstone, corundum and other gems.
Austria
Austria: Tyrol / Zillertal
Significant
Known for alpine minerals and gem crystals.
Inclusions & features
Zoning Color Zoning
Under 10x loupe in immersion: bands or patches of deeper or lighter color arranged…
Crystals Crystal Inclusions
Under 10x loupe: solid, well-formed mineral crystals trapped inside the host gem. They may…
Fractures Fingerprint Inclusions
Under 10x loupe: curved or wavy lines of tiny dots forming patterns that look…
Fractures Feathers and Fractures
Under 10x loupe: irregular internal surfaces that catch light and appear bright, wing-like, or…
Instruments used
Refractometer
Measures refractive index, the backbone of gem identification
Polariscope
Determines single vs. double refraction, quick and conclusive
Hydrostatic Scale
Measures specific gravity, works even on opaque stones
10x Loupe
Your most-used instrument, start every examination here
Dichroscope
Reveals pleochroism, instantly eliminates singly-refractive stones