Spinel Gemstone & Information | Gemopedia by JTV | Gemopedia™

Spinel

Naturally dazzling spinel has graced the pages of history and many royal crowns due to its resemblance to ruby. Today, however, spinel stands on its own as a remarkable gem. Spinel comes in a wide range of stunning hues and can also exhibit optical phenomena like asterism and color-change. It is generally underappreciated compared to other colored stones, lending itself to more affordable prices, but this gem, said in Burma to be polished by the spirits, has a beauty that is difficult to ignore.

Colors

Red, Pink, Bluish Violet To Greenish Blue, Purple, Lavender, Blue, Bluish-Green, Brown, Black, Colorless, Green, Orange, Yellow

  • Spinel classification

    CommonName
    Spinel
    Species
    Spinel
    Variety
    Colors
    Red, Pink, Bluish Violet To Greenish Blue, Purple, Lavender, Blue, Bluish-Green, Brown, Black, Colorless, Green, Orange, Yellow
    AlternateNames
    Flame Spinel, Rubicelle, Ceylonite, Pleonaste
    GemstoneGroups
    KeySeparations
    refractive index, SR nature, magnification and spectrum. An accurate RI reading can distinguish natural from synthetic spinel, which usually has a higher RI. Red spinel often shows a chromium spectrum with lines in the red, possibly as emission lines.
    ClassificationComments
    Spinel frequently occurs in an octahedral form with triangular etch pits on the faces. Also appears in a flat twinned form as a macle. Flame spinel or rubicelle: orange, orange-red to yellowish red spinel usually from Brazilceylonite: dingy blue, gray to black with no iron contentpleonaste: opaque very dark blue or green to black containing iron. Misnomers: Balas ruby, spinel ruby, almandine spinel, sapphire spinel, sapphirine. Blue and red spinel tends to be on the higher side of the RI limit.
  • Spinel chemistry & crystallography

    ChemicalName
    magnesium aluminum oxide
    ChemicalFormula
    MgAl2O4
    Synthesis
    CrystalSystem
    Cubic
    ChemistryClassification
    Oxide
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Spinel optical properties

    Transparency
    Transparent - Opaque
    Dispersion
    Strength: moderate fire Value: 0.02
    OpticalComments
    RefractiveIndex
    1.718
    Birefringence
    0-0
    OpticCharacter
    NA
    OpticSign
    NA
    PolariscopeReaction
    Singly Refractive (SR) With ADR
    Fluorescence
    SWUV: Variable
    LWUV: Variable
    CCFReaction
    Pink to red: inert to fluorescent red. Rare blue with cobalt: reddish inert if iron type
    Pleochroism
  • Spinel characteristic physical properties

    Hardness
    8
    CharacteristicComments
    Streak
    SpecificGravity
    3.57-3.7 Range:0.1/-0.03 Typical:3.6
    Toughness
    Varies
    Inclusions
    Spinel is a type II clarity stone. Stones might contain natural mineral inclusions like spinel or apatite, needles, negative crystals in the shape of an octahedral, fingerprints and iron oxide staining.
    Luster
    SubAdamantine
    Stability
    Very Good
    Fracture
    Conchoidal
    Cleavage
    None