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January Birthstone

Umbalite Polished
Umbalite Classification
Common Name Umbalite
Species Garnet
Umbalite Optical Properties
Transparency Opaque-Transparent
Dispersion Strength: Moderate Fire Value: 0.022
Refractive Index Over The Limit 1.730-1.820
Optic Character NA
Optic Sign NA
Polariscope Reaction Anomalous Double Refraction (ADR), Singly Refractive (SR)
Fluorescence SWUV: Inert
LWUV: Inert
Pleochroism None
Umbalite Characteristic Physical Properties
Streak None
Toughness Good
Inclusions Crystals
Luster Vitreous
Fracture Conchoidal, Uneven
Cleavage None
Umbalite Chemistry & Crystallography
Chemical Name Magnesium Iron Manganese Aluminum Silicate
Chemical Formula (Mg,Fe, Mn)3Al2(SiO4)3
Crystal System Cubic
Chemistry Classification Silicate

Umbalite Colors

  • Brown Umbalite Brown
  • Purple Umbalite Purple
  • Pink Umbalite Pink
  • Red Umbalite Red

Countries of Origin

Tanzania, United Republic Of

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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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Tim Matthews


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.