Cobalt-Lead Glass Filled Sapphire Gemstone & Information | Gemopedia by JTV | Gemopedia™
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.
Cobalt-lead-glass-filled-sapphire classificationCommonNameCobalt-Lead Glass Filled SapphireSpeciesCorundumVarietySapphireColorsBlueAlternateNamesGemstoneGroupsKeySeparationsChelsea filter reaction, dark field magnification, RI, birefringence, pleochroismClassificationCommentsThe 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 & crystallographyChemicalNamealuminum oxideChemicalFormulaAl2O3SynthesisCrystalSystemTrigonalChemistryClassificationOxideNatureNaturalCrystallinityCrystallineChemistryComments
Cobalt-lead-glass-filled-sapphire optical propertiesTransparencyTransparent - OpaqueDispersionStrength: moderate fire Value: 0.018OpticalCommentsRefractiveIndex1.762-1.77Birefringence0.008-0.01OpticCharacterUniaxialOpticSignNegativePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV: inert
LWUV: inertCCFReactionredPleochroismDichroic, violet blue and greenish blue
Cobalt-lead-glass-filled-sapphire characteristic physical propertiesHardness9CharacteristicCommentsStreakWhiteSpecificGravity3.95-4.1 Typical:4ToughnessPoorInclusionsCobalt-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.LusterSubAdamantineStabilityPoorFractureConchoidalCleavageNone