Watermelon Tourmaline
Watermelon tourmaline (elbaite) has a pink to red core surrounded by a green rim. The gradual color transition is a separation indicator from doublets or assembled stones. Typically cut as slices or cross-sections to display the pattern.
Physical & Optical Properties
RI Range1.616–1.650
SG Range3.00–3.10
SG Typical3.06
Hardness (Mohs)7–7.5
Crystal SystemTrigonal
Optic CharacterDR Uniaxial (−)
Birefringence0.018
Dispersion0.017
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismStrong Dichroic
ColorsMulti, Red Pink, Green
SpeciesTourmaline
VarietyElbaite (Bicolor)
Related: Tourmaline Varieties
Key Differentiators
- Distinctive pink/red core with green rim — bicolor zoning visible under loupe and to naked eye
- Gradual color transition zone (not sharp as in ametrine) between pink core and green rim
- Tourmaline RI/SG confirms species; bicolor pattern is characteristic
- Commonly cut as cross-sections or slices perpendicular to c-axis to display watermelon pattern
- Strong dichroism in each color zone; growth tubes parallel to c-axis under magnification
Common Simulants
- Bicolor Glass: Isotropic, gas bubbles, swirl marks; no natural inclusions; abrupt color junction or gradation is manufactured
- Pink-Green Tourmaline Doublet: Two stones cemented together; cement layer visible under immersion; inclusions terminate at boundary; RI may be consistent if both pieces are tourmaline
- Bicolor Synthetic Corundum: RI 1.762–1.778, SG 4.00; much higher RI and SG; curved growth lines under magnification; no natural tourmaline inclusions
Treatments
- Heat Treatment
- Irradiation
- Surface Coating
Price Context
Natural — low ($/ct)$50
Natural — high ($/ct)$500
NoteSlice or cross-section cuts $50–300/ct; fine faceted watermelon sections with vivid colors $100–500/ct. Clarity and color contrast are key value factors.
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
About Watermelon Tourmaline
Watermelon tourmaline (elbaite) has a pink to red core surrounded by a green rim. The gradual color transition is a separation indicator from doublets or assembled stones. Typically cut as slices or cross-sections to display the pattern.
Identifying a watermelon tourmaline? GemID walks through these tests in order — RI, SG, fluorescence, and more.
Try GemID Free →