Hessonite Garnet
Last updated: April 2026
Grossular is a calcium-aluminium garnet; the orange-brown variety is called Hessonite. Under 10× magnification, hessonite typically shows a distinctive "treacle effect" — a roiled, heat-shimmer appearance caused by diopside and apatite inclusions. This is diagnostic; no other orange stone shows this.
Physical & Optical Properties
RI Range1.730–1.760
SG Range3.59–3.65
SG Typical3.61
Hardness (Mohs)7–7.5
Crystal SystemCubic
Optic CharacterSR (Singly Refractive)
Dispersion0.028
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismNone
ColorsYellow Orange, Brown, Green, Red Pink, Colorless
SpeciesGarnet
VarietyGrossular / Hessonite
Related: Garnet Varieties
Key Differentiators
- Treacly or roiled internal appearance
- Wide color range
- Tsavorite is the green variety
Common Simulants
- Citrine: Citrine is uniaxial negative DR; RI 1.544–1.553; SG 2.65; lower RI than hessonite (~1.742).
- Spessartite Garnet: Higher RI (1.810); stronger orange hue typically; isotropic like hessonite — difficult without refractometer.
- Glass: Gas bubbles, swirl marks under loupe; isotropic but SG varies widely; conchoidal fracture.
Commonly Confused With
Commonly confused with: Citrine, Spessartite Garnet, Glass, Padparadscha Sapphire.
Treatments
- Polymer / Resin Infusion (documented — GIA 2016)
- Heat Treatment (occasional — undetectable)
Price Context
Natural — low ($/ct)$10
Natural — high ($/ct)$100
NotePer carat; hessonite (orange-brown cinnamon stone) and other grossular varieties; tsavorite priced separately
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a hessonite garnet? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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