Tourmaline · Variety of Tourmaline
Bicolor Tourmaline
Two distinct color zones in one stone; most often pink-green, though any combination occurs
Bicolor
Green
Pink
Optical characteristics
- Ref. index
- 1.62 – 1.64
- Birefringence
- 0.018 – 0.04
- Luster
- Vitreous
- Pleochroism
- Strong Strong; each color zone shows its own dichroism independently.
- Fluorescence
- Inert.
Source localities
Brazil
Brazil: Minas Gerais / Paraíba / Bahia
Significant
Major source for beryl, tourmaline, quartz, topaz, chrysoberyl and rare minerals.
Afghanistan
Afghanistan: Panjshir / Nuristan / Badakhshan
Significant
Known for emerald, tourmaline, kunzite, lapis lazuli and rare minerals.
Nigeria
Nigeria: Oyo / Ogun / Plateau fields
Significant
Important source for tourmaline, sapphire, garnet, beryl and topaz.
Mozambique
Mozambique: Montepuez / Alto Ligonha / Cuamba
Significant
Major modern source for ruby, garnet, tourmaline and Paraíba-type tourmaline.
Enhancement & treatment
Inclusions & features
Needles Growth Tubes, Rain Inclusions
Under 10x loupe: long thin hollow channels running parallel to each other and to…
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…
Instruments used
Refractometer
Measures refractive index, the backbone of gem identification
Dichroscope
Reveals pleochroism, instantly eliminates singly-refractive stones
10x Loupe
Your most-used instrument, start every examination here
Polariscope
Determines single vs. double refraction, quick and conclusive
Immersion Microscope
See every internal detail clearly, the professional standard
High CRI Penlight
Tiny concentrated white spot for field checks, inclusions, fire, and fractures