Tourmaline
Last updated: April 2026
Elbaite tourmaline occurs in a wide range of colors with strong pleochroism. Named color varieties: Rubellite (red/pink), Indicolite (blue), Verdelite (green), Paraiba (neon blue-green, Cu-bearing), Watermelon (pink core, green rim), Chrome Tourmaline (Cr-green). All share the same species RI/SG and cannot be distinguished by standard measurements alone — color and provenance separate them.
Physical & Optical Properties
RI Range1.624–1.644
SG Range3.01–3.26
SG Typical3.06
Hardness (Mohs)7–7.5
Crystal SystemTrigonal
Optic CharacterDR Uniaxial (−)
Birefringence0.020
Dispersion0.017
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterVariable
PleochroismStrong Dichroic
ColorsRed Pink, Green, Blue Violet, Yellow Orange, Brown, Black, Colorless, Multi
SpeciesTourmaline
Related: Tourmaline Varieties
Key Differentiators
- Strong pleochroism
- Elongated crystals with striations
- Liquid-filled inclusions (trichites)
Common Simulants
- Emerald: Emerald: uniaxial negative; RI 1.577–1.583; SG 2.72; Chelsea filter red; characteristic jardin inclusions.
- Ruby: Ruby: uniaxial negative; RI 1.762–1.778; SG 4.00; Chelsea filter strongly red; strong UV fluorescence.
- Sapphire: Sapphire: uniaxial negative; RI 1.762–1.778; SG 4.00; much higher RI than tourmaline.
- Glass: Isotropic; gas bubbles under loupe; no pleochroism; conchoidal fracture.
Commonly Confused With
Commonly confused with: Emerald, Ruby, Sapphire, Glass, Almandine Garnet, Peridot, Tsavorite Garnet.
Treatments
- Heat Treatment (to lighten or clarify)
- Irradiation (to deepen color)
- Surface Coating (Paraiba imitation)
Price Context
Natural — low ($/ct)$50
Natural — high ($/ct)$2,000
NotePer carat; Paraíba (neon blue-green, Cu-bearing) can exceed $50,000/ct; chrome tourmaline and rubellite also premium
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a tourmaline? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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