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HESSONITE GARNET

Introduction: Hessonite is a variety of the grossular garnet species of the garnet family.

Colors: medium to dark yellow-orange to reddish-orange

Clarity: Hessonite garnets are of clarity Type II. Gems in this type typically grow with some minor inclusions in nature that may be eye visible but usually are well hidden or require magnification.
Hessonite commonly shows a “heat wave” or roiled effect.

Stone Sizes: Reddish-orange hessonites have been found in the Sri Lankan gem gravels up to several hundred carats but most hessonites from Sri Lanka are less than 20 carats and most Canadian
hessonites are less than 10 carats.

Localities: Sri Lanka, Canada. Minor amounts can be found in Brazil, Mexico and the United States

Treatments: None

Gemology:
-Refractive Index: 1.740 (+0.020,-0.010)
-Birefringence: None (singly refractive)
-Optic Character: Singly refractive, often shows anomalous double refraction (ADR)
-Dispersion: 0.028
Specific Gravity: 3.61 (+0.12, -0.04)
-Hardness: 7-7.5
-Toughness: Fair to good
-Chemical Composition: Ca3Al2(SiO4)3
-Cause of Color: iron
-Absorption Spectra: sometimes bands are seen at 4070 and 4300
-Fluorescence: None
-Cleavage: None
-Phenomena: None

Name: Hessonite is from a Greek word meaning inferior because of its lower hardness.

Dates: All species of garnets can be used as the birthstone for January. Garnets are also the gem of
choice for second anniversaries.

Care: Ultrasonics are usually safe but risky with liquid inclusions. Steam cleaners should never be used.
The safest method for cleaning is with warm soapy water. Abrupt temperature changes will likely cause
fracturing.


To see available hessonites, click here.