Cobalt-Lead Glass Filled Sapphire Gemstone & Information | Gemopedia by JTV | Gemopedia™

Cobalt-Lead Glass Filled Sapphire

Cobalt-lead glass filled sapphire has been filled through a process similar to "infilling" using lead glass. Performed at low heat, this is a less durable treatment and should be treated gently, avoiding household and professional chemicals. This treatment, which uses cobalt-colored lead glass, improves clarity, color, and may add weight through the filling of voids and fissures.

Colors

Blue

  • Cobalt-lead-glass-filled-sapphire classification

    CommonName
    Cobalt-Lead Glass Filled Sapphire
    Species
    Corundum
    Variety
    Sapphire
    Colors
    Blue
    AlternateNames
    GemstoneGroups
    KeySeparations
    Chelsea filter reaction, dark field magnification, RI, birefringence, pleochroism
    ClassificationComments
    The stone is cobalt blue instead of the natural blue of sapphire. Lead glass will be damaged with jeweler's torch or exposure to chemicals. Specific gravity can be increased to to the amount of glass in the stone.
  • Cobalt-lead-glass-filled-sapphire chemistry & crystallography

    ChemicalName
    aluminum oxide
    ChemicalFormula
    Al2O3
    Synthesis
    CrystalSystem
    Trigonal
    ChemistryClassification
    Oxide
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Cobalt-lead-glass-filled-sapphire optical properties

    Transparency
    Transparent - Opaque
    Dispersion
    Strength: moderate fire Value: 0.018
    OpticalComments
    RefractiveIndex
    1.762-1.77
    Birefringence
    0.008-0.01
    OpticCharacter
    Uniaxial
    OpticSign
    Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: inert
    LWUV: inert
    CCFReaction
    red
    Pleochroism
    Dichroic, violet blue and greenish blue
  • Cobalt-lead-glass-filled-sapphire characteristic physical properties

    Hardness
    9
    CharacteristicComments
    Streak
    White
    SpecificGravity
    3.95-4.1 Typical:4
    Toughness
    Poor
    Inclusions
    Cobalt-lead glass filled sapphire will have gas bubbles and will display purplish red flash colors from the lead glass filling. There will be color concentrations in the fissures of the stone.
    Luster
    SubAdamantine
    Stability
    Poor
    Fracture
    Conchoidal
    Cleavage
    None