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Gemstone Crystal System Density Hardness Refractive index Treatments
Demantoid
cubic 3.84 6.5 - 7 1.89 heat


demantoid

Color:
Light to Dark green and yellowish green

Clarity: Type II
Optic Character:
SR, often ADR
Cause of Color: Cr, Fe
Fluorescence: Inert
Fracture : Concoidal
to uneven
Luster : Vitreous
Cleavage :
None
Durability: Fair to Good

Characteristics for Identification:
Horsetail (byssolite) inclusions, high dispersion

Localities:
Italy, Korea, Rusia, Zaire

demantoid crystal


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Demantoid
A Vaiety of Andradite Garnet
Ca3 Fe2 Si3 O12

Demantoid is a member of the garnet family. It is not only the most expensive of the garnets, it is one of the most expensive gems in the world! It is coveted for its rarity and its incredible brilliance. Demantoid is more dispersive than diamond. It's ability to break white light into rainbow colors is unsurpassed.
Demantoid occurs in many shades of green and ranges from slightly yellowish green to brownish green with a golden shine. The rarest and most valuable is a deep emerald green. Only a few stones achieve more than two carats after cutting. Demantoids from the Urals often include the diagnostic inclusions of asbestos fibres known as "horsetails". These inclusions are desirable.

Demantoid was first discovered in the Urals mountains in Russia in 1868.

Garnet Group

Almandite
Andradite
Grossular
Pyrope
Spessartite
Uvaravite
This gemstone is often confused with:

Peridot
Tsavorite
Emerald
Tourmaline
Sphene
Shalerite
Glass
Plastic