Spinel Gemstone & Information | Gemopedia by JTV | Gemopedia™
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.
Red, Pink, Bluish Violet To Greenish Blue, Purple, Lavender, Blue, Bluish-Green, Brown, Black, Colorless, Green, Orange, Yellow
Spinel classificationCommonNameSpinelSpeciesSpinelVarietyColorsRed, Pink, Bluish Violet To Greenish Blue, Purple, Lavender, Blue, Bluish-Green, Brown, Black, Colorless, Green, Orange, YellowAlternateNamesFlame Spinel, Rubicelle, Ceylonite, PleonasteGemstoneGroupsKeySeparationsrefractive 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.ClassificationCommentsSpinel 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 & crystallographyChemicalNamemagnesium aluminum oxideChemicalFormulaMgAl2O4SynthesisCrystalSystemCubicChemistryClassificationOxideNatureNaturalCrystallinityCrystallineChemistryComments
Spinel optical propertiesTransparencyTransparent - OpaqueDispersionStrength: moderate fire Value: 0.02OpticalCommentsRefractiveIndex1.718Birefringence0-0OpticCharacterNAOpticSignNAPolariscopeReactionSingly Refractive (SR) With ADRFluorescenceSWUV: Variable
LWUV: VariableCCFReactionPink to red: inert to fluorescent red. Rare blue with cobalt: reddish inert if iron typePleochroism
Spinel characteristic physical propertiesHardness8CharacteristicCommentsStreakSpecificGravity3.57-3.7 Range:0.1/-0.03 Typical:3.6ToughnessVariesInclusionsSpinel 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.LusterSubAdamantineStabilityVery GoodFractureConchoidalCleavageNone