Ruby (Cat's-Eye) Gemstone & Information | Gemopedia by JTV | Gemopedia™

Ruby (Cat's-Eye)

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.

Colors

Orangy Red To Purplish Red

  • Ruby-cats-eye classification

    CommonName
    Ruby (Cat's-Eye)
    Species
    Corundum
    Variety
    Cat's-Eye Ruby
    Colors
    Orangy Red To Purplish Red
    AlternateNames
    GemstoneGroups
    KeySeparations
    Appearance, RI and magnification
    ClassificationComments
    Stone usually cut as cabochons.
  • Ruby-cats-eye chemistry & crystallography

    ChemicalName
    aluminum oxide
    ChemicalFormula
    Al2O3
    Synthesis
    CrystalSystem
    Trigonal
    ChemistryClassification
    Oxide
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Ruby-cats-eye optical properties

    Transparency
    Semitransparent To Opaque
    Dispersion
    Strength: moderate fire Value: 0.018
    OpticalComments
    RefractiveIndex
    1.762-1.77
    Tolerance: (+0.009/-0.005)
    Birefringence
    0.008-0.01
    OpticCharacter
    Uniaxial
    OpticSign
    Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Weak to strong red, stronger under SWUV. Slightly weaker than synthetic ruby.Heated ruby might have chalky fluorescence
    LWUV: Weak to strong red
    CCFReaction
    Pleochroism
    Unobservable
  • Ruby-cats-eye characteristic physical properties

    Hardness
    9
    CharacteristicComments
    Streak
    White
    SpecificGravity
    4.1-3.95 Typical: 4
    Toughness
    Varies
    Inclusions
    Cat'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.
    Luster
    SubAdamantine
    Stability
    Very Good
    Fracture
    Conchoidal
    Cleavage
    None