Demantoid

saf-ahyuh r

Demantoid garnet is one of the most desirable of all colored gemstones and extremely rare. A color variety of andradite garnet, the name demantoid originates from the old German word demant meaning "diamond-like," because of a luster and dispersion that yields a fire even higher than diamonds.

Demantoid Polished
Demantoid Classification
Common Name Demantoid
Species Garnet
Demantoid Optical Properties
Transparency Transparent - Opaque
Dispersion Strength: Strong Fire Value: 0.57
Refractive Index 1.888-0.000
Optic Character NA
Optic Sign NA
Polariscope Reaction Singly Refractive (SR) With ADR
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism None
Demantoid Characteristic Physical Properties
Hardness 6.5-7
Specific Gravity 3.810-3.870 Range:0.03/-0.03 Typical:3.840
Toughness Poor
Inclusions Demantoid garnet is a type II clarity stone. Stones might show surface abrasions. Some stones might contain fibrous chysotile asbestos or "horsetail inclusions". Namibian stones might show stress fractures.
Luster SubAdamantine, Vitreous
Stability Good
Fracture Conchoidal, Uneven
Cleavage None
Demantoid Chemistry & Crystallography
Chemical Name calcium iron silicate
Chemical Formula Ca3Fe2(SiO4)3
Crystal System Cubic
Chemistry Classification Silicate

Demantoid Colors

  • Brown Demantoid Brown
  • Green Demantoid Green

Demantoid Spectra

Demantoid Spectra
DEMANTOID GARNET

Color due to chromium and iron. Absorption of the blue up to 460nm masking the more typical 443nm line. Fine lines in red at 620nm, 632nm,693nm and 700nm are very difficult to detect. This is due to the high chromium content in this stone

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Countries of Origin

Afghanistan; Iran (Islamic Republic of); Pakistan; Turkey; Unknown; Namibia; Russian Federation (the); Madagascar; Kenya; Nigeria

History

In the gemstone universe there are many desirable, beautiful stones. Demantoid is one that stands with the best and the brightest. First, it is extremely rare because it is a color variety of the andradite garnet. Let's start with its green... delicious, deep-lime shades with golden-yellow flashes. The range goes from the most intense to more moderate shades. Wherever your stone lands in depth of shading, it will still hold the essence of that incomparable green, for which it can thank chromium. Demantoid is also revered for its diamond-like sheen, in fact, its name comes from the German "demant" meaning diamond-like. Well-cut demantoid has superior sparkle and fire, which makes it a very satisfying gem to own and wear. The rarest, and therefore most expensive, of all demantoids have a golden, whip-like inclusion called a horsetail. Most frequently seen in Russian stones, horsetails have been present in stones from Italy and Iran as well. This gem was originally mined in Russia around the mid-19th century before mining ceased at the time of the 1917 Russian Revolution. We are delighted that independent miners are discovering stream-worn demantoids in several areas around Ekaterinburg today. Slowly, these newly found stones are finding their way into the marketplace.

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More About Demantoid

Once revered as the Czar of the garnet family, the demantoid has many historical ties to the court of Nicolas II of Russia. Demantoid's regal past includes the works of Karl Fabergé. Perhaps the lush green of the demantoid accounts for the historical belief that it could boost vitality

Demantoid Gemstone

Sisk Gemology Reference

Showcasing 200 gemstones in over 1,000 pages and accompanied by more than 2,000 photos, The Sisk Gemology Reference is a must-have in every collector’s library. Each comprehensive, three-volume set features state-of-the-art photography, detailed illustrations, and scientifically precise descriptions to create an entrancing experience for gemstone amateurs and afficionados alike.

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Optical Phenomena

Cat's-Eye

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case demantoid garnet. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line.Demantoid garnets that feature a cat's eye are rare.

Cat's-Eye Demantoid
Cat's-Eye Classification
Common Name Cat's-Eye
Cat's-Eye Characteristic Physical properties
Inclusions Cat's-eye demantoid garnet is type II clarity stone. Chatoyancy is caused by parallel needles. Due to the stones low mohs hardness it might have scratches and abrasions. Fibrous asbestos "horsetail inclusions" in Russian material. Stress fractures in Namibian stones.
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.