Archive for the Corundum Category

  • Star Sapphire

    Refractive Index : 1.770 – 1.762 (+0.009 – 0.005)

    Optical Characteristic : DR U-, AGG

    Specific Gravity : 4.00 (+0.10 – 0.05)

    Formula : AI2O3

    Crystal System : Trigonal

    Variety/Species : Sapphire

    Species/Group : Corundum

    Birefringence : 0.008 to 0.010

    Dispersion : 0.018

    Hardness : 9

    Toughness : Good to excellent

    Ultrasonic : Usually safe

    Steam : usually safe

    UV Long : Inert to strong

    UV Short : Inert [...]

  • Ruby

    Refractive Index : 1.770 – 1.762 (+0.009 – 0.005)

    Optical Characteristic : DR, uniaxial negative

    Specific Gravity : 4.00 (+0.10 – 0.05)

    Formula : AI2O3

    Crystal System : Trigonal

    Variety/Species : Ruby

    Species/Group : Corundum

    Birefringence : 0.008 to 0.010

    Dispersion : 0.018

    Hardness : 9

    Toughness : Excellent

    Ultrasonic : Usually safe

    Steam : Usually safe

    UV : Burma Ruby : Strong red (LW), moderate red (SW)
    Ceylon [...]

  • Yellow Sapphire

    Natural Yellow Sapphire Gemstone

    Refractive Index : 1.770 – 1.762 (+ 0.009 – 0.005)

    Optical Characteristic : DR Uniaxial negative

    Specific Gravity : 4.00 (+ 0.10 – 0.05)

    Formula : AI2O3

    Crystal System : Trigonal

    Variety/Species : Sapphire

    Species/Group : Corundum

    Birefringence : 0.008 to 0.010

    Dispersion : 0.018

    Hardness : 9

    Toughness : Excellent

    Ultrasonic : Uaually safe

    Steam : Usually safe

    UV Long : Inert to [...]