Heliodor
Last updated: April 2026
The yellow to greenish-yellow variety of beryl, colored by iron (Fe³⁺). Also called Golden Beryl when a pure yellow. Heliodor refers to yellowish-green to golden-yellow stones. Distinguished from citrine by higher RI and SG; from yellow sapphire by lower RI/SG and uniaxial character; from yellow chrysoberyl by lower RI/SG.
Heliodor has a specific gravity of 2.72 and a refractive index of 1.568–1.580, with a Mohs hardness of 7.5–8.0. It is uniaxial −.
Physical & Optical Properties
Measured with a polariscope, a refractometer, a hydrostatic balance, a Chelsea filter, a UV torch, a loupe, a darkfield loupe and a spectroscope — step-by-step for each.
Through the refractometer
Drawn from the refractive index above, on a 1.40–1.81 scale. How to take this reading.
Related: Beryl Varieties
Key Differentiators
- Beryl RI and SG — separates from all yellow simulants
- Uniaxial negative — distinct from biaxial topaz and yellow sapphire
- Weak pleochroism (pale yellow / greenish-yellow)
Natural vs. Synthetic
Synthetic heliodor is commercially available (Hydrothermal). Distinguishing natural from synthetic typically requires microscopic examination of internal features.
- General Note: No commercial synthetic heliodor. Confirm beryl species: RI 1.568–1.580, SG ~2.72, uniaxial negative. Separation from simulants is via RI/SG — citrine (RI 1.544), topaz (RI 1.609–1.643), chrysoberyl (RI 1.746) all differ decisively. Synthetic: Irradiated aquamarine: blue-green beryl irradiated to yellow; same properties as natural heliodor. Irradiation origin is not detectable by standard gemological means.
Loupewise Pro includes a two-phase natural vs. synthetic testing protocol for Heliodor.
Common Simulants
- Citrine: Citrine: uniaxial negative DR; RI 1.544–1.553; SG 2.65. Much lower RI than heliodor — decisive separation on refractometer.
- Yellow topaz: Topaz: biaxial positive; perfect basal cleavage; SG 3.53; RI 1.609–1.643. Higher RI, much higher SG, biaxial — all distinct from heliodor.
- Yellow chrysoberyl: Chrysoberyl: biaxial positive; RI 1.746–1.755; SG 3.70–3.78. Much higher RI and SG than heliodor.
Commonly Confused With
Commonly confused with: Citrine, Yellow Topaz, Chrysoberyl.
Treatments
- Irradiation — induces or intensifies yellow/golden color
Measurement Guides
Identifying a heliodor? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.
Try Loupewise Free →Studying for the GIA, FGA, or FEEG practical? Heliodor is one of the 132 species in Loupewise’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
Practice exams →