Ruby (Cat's-Eye) Gemstone & Information | Gemopedia by JTV | Gemopedia™
The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case ruby. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light through the crystal, scattering and reflecting light back to the viewer as a thin line.
Orangy Red To Purplish Red
Ruby-cats-eye classificationCommonNameRuby (Cat's-Eye)SpeciesCorundumVarietyCat's-Eye RubyColorsOrangy Red To Purplish RedAlternateNamesGemstoneGroupsKeySeparationsAppearance, RI and magnificationClassificationCommentsStone usually cut as cabochons.
Ruby-cats-eye chemistry & crystallographyChemicalNamealuminum oxideChemicalFormulaAl2O3SynthesisCrystalSystemTrigonalChemistryClassificationOxideNatureNaturalCrystallinityCrystallineChemistryComments
Ruby-cats-eye optical propertiesTransparencySemitransparent To OpaqueDispersionStrength: moderate fire Value: 0.018OpticalCommentsRefractiveIndex1.762-1.77
Tolerance: (+0.009/-0.005)Birefringence0.008-0.01OpticCharacterUniaxialOpticSignNegativePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV: Weak to strong red, stronger under SWUV. Slightly weaker than synthetic ruby.Heated ruby might have chalky fluorescence
LWUV: Weak to strong redCCFReactionPleochroismUnobservable
Ruby-cats-eye characteristic physical propertiesHardness9CharacteristicCommentsStreakWhiteSpecificGravity4.1-3.95 Typical: 4ToughnessVariesInclusionsCat's-eye rubies will have silk or sets of parallel rutile needles, hexagonal growth lines, color zoning, liquid, negative and mineral inclusions. Some stone might show twinning.LusterSubAdamantineStabilityVery GoodFractureConchoidalCleavageNone