Pure crimson red,brick-red, to traffic-light red, colored by chromium substituting for aluminum with strong red organ-pipe fluorescence under...
Chemical formula
MgAl₂O₄ + Cr³⁺ (Magnesium Aluminum Oxide with Chromium)
Spinel • Spinel
Cobalt Blue Spinel
Intense electric royal to neon blue caused by trace divalent cobalt (Co2+), distinct from common grayish-blue iron-colored spinel.
MgAl₂O₄ + Co²⁺ (± Fe²⁺)Mohs 8.0 Mohs
Mineralogical & Gemological Profile
| Mineral Family | Spinel |
|---|---|
| Mineral Species | Spinel |
| Gemological Variety | Cobalt-Bearing Blue Spinel |
| Chemical Composition | MgAl₂O₄ + Co²⁺ (± Fe²⁺) |
| Crystal System | Isometric |
| Mohs Hardness | 8.0 Mohs |
| Specific Gravity | 3.58 – 3.64 |
| Refractive Index | 1.718 |
Color Characteristics & Optical Behavior
Intense electric royal to neon blue caused by trace divalent cobalt (Co2+), distinct from common grayish-blue iron-colored spinel.
Geological Context & Pakistani / Global Localities
Extremely rare marble-hosted occurrences in Vietnam (Luc Yen), Sri Lanka, Tanzania, and localized Himalayan marbles.
Collector Interest & Rarity Factors
Genuine natural cobalt-bearing spinel is one of the rarest blue gemstones on Earth, prized for its vivid glow even in low lighting.
Fine Jewelry Applications
High-value collector rings and bespoke creations.
Treatment Considerations & Disclosure
Natural cobalt spinels are typically unheated; HOWEVER, synthetic flame-fusion and flux-grown cobalt spinels are widespread in the market. Laboratory verification is mandatory before claiming natural cobalt origin.
Care & Cleaning Instructions
Clean gently with warm soapy water and a soft brush.
Traditional Meaning
Traditional Symbolism & Cultural Heritage
Symbolizes rarity, discernment, and clarity of vision. August birthstone.
Note: Cultural and birthstone traditions are presented strictly as historical folklore, never as scientifically verified medical or metaphysical effects.
Spinel
Related Entries
Glowing neon hot-pink to electric pinkish-red with virtually zero dark tone ('no dark side'), caused by high chromium...
Chemical formula
MgAl₂O₄ + Cr³⁺ (Very low Iron content)