Black Spinel
Spinel (variety: Black) · Semi-Precious Gemstone
Crystal System
Cubic (Isometric); typically occurs as octahedral crystals or massive forms.
Mineral Group
Oxides (Spinel Group)
Chemical Formula
MgAl2O4 (often with iron or chromium substitution for magnesium/aluminum)
Formation Process
Forms primarily through regional metamorphism of limestone and dolostone, or as a primary mineral in mafic igneous rocks and pegmatites.
About This Crystal
Opaque, jet-black appearance with a high vitreous to sub-adamantine luster. In this jewelry piece, the stones are faceted into small rounds (melee) set in a pave or shared-prong arrangement.
Physical Characteristics
Color is solid black; streak is white; no cleavage; conchoidal fracture; specific gravity 3.6 - 4.1; typically non-fluorescent; lacks magnetism unless iron-rich.
Optical Properties
Isotropic (singly refractive); refractive index 1.710–1.740; lacks pleochroism and birefringence; no dispersion visible due to opacity.
Hardness & Durability
Origin Region
Notably sourced from Thailand, Sri Lanka, Myanmar (Burma), Vietnam, and Brazil.
Hardness & Durability
Mohs hardness of 8; high toughness; excellent stability; very durable for daily jewelry wear compared to softer black stones like onyx or jet.
Care & Maintenance
Clean with warm soapy water or ultrasonic cleaners; avoid harsh acids despite high stability; store separately to prevent scratching softer metals or gems.
Rarity & Value
Relatively affordable and common in small sizes; value is driven by the quality of the cut and 'jet black' saturation without grayish or brownish secondary tones.
Special Characteristics
Notable for its superior luster and hardness compared to other black gemstones; sometimes referred to as 'Black Prince's Ruby' cousin due to its mineral relationship.
Lore & History
Historically used as a protective stone to repel negativity; in ancient times, it was often confused with black tourmaline or onyx but favored for its brilliance; associated with the Root Chakra in modern crystal lore.