Quartz
Prasiolite
Pale to medium green, often called green amethyst
Green
Pale Green
Optical characteristics
- Ref. index
- 1.544 – 1.553
- Birefringence
- 0.009
- Luster
- Vitreous
- Pleochroism
- Weak Weak dichroism: slightly different shades of green to near-colorless depending on viewing direction.
- Fluorescence
- Inert.
Source localities
Bolivia
Bolivia: Anahi Mine
Significant
Classic source for ametrine; also produces amethyst that is heat-treated to prasiolite.
Brazil
Brazil: Minas Gerais / Paraíba / Bahia
Significant
Major source for beryl, tourmaline, quartz, topaz, chrysoberyl and rare minerals.
Canada
Canada: British Columbia / NWT / Labrador
Significant
Known for nephrite jade, diamonds and labradorite.
United States
USA: major gem fields
Commercial
Diverse sources for turquoise, tourmaline, opal, sapphire, topaz, red beryl and rare minerals.
Spain
Spain: Salamanca / Iberian quartz localities
Commercial
Known for quartz and regional gem materials.
Enhancement & treatment
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…
Crystals Negative Crystals
Under 10x loupe: an empty cavity that has the geometric shape of the host…
Instruments used
Refractometer
Measures refractive index, the backbone of gem identification
10x Loupe
Your most-used instrument, start every examination here
Polariscope
Determines single vs. double refraction, quick and conclusive
UV Lamp, Long Wave and Short Wave
Fluorescence exposes treatments, synthetics, and origin