Archive for the Natural Gemstones Category

  • Smoky Quartz

    Refractive Index : 1.553 – 1.544

    Optical Characteristic : DR, U+, AGG

    Specific Gravity : 2.651 (+0.04 – 0.01)

    Formula : SiO2

    Crystal System : Trigonal

    Variety/Species : smoky

    Species/Group : Quartz

    Birefringence : 0.009

    Dispersion : 0.013

    Hardness : 7

    Toughness : good

    Ultrasonic : Usually safe

    Steam : risky

    UV Long : Inert

    UV Short : Inert

    Pleochroism : 2 colors

    Strength : weak

    Pleochroism Colors : Dark stones, weak: [...]

  • Spinel – Synthetic

    Refractive Index : 1.728 (+0.012 – 0.008)

    Optical Characteristic : SR, ADR

    Specific Gravity : 3.64 (+0.02 – 0.12)

    Formula : MgAI2O4

    Crystal System : Cubic

    Variety/Species : All

    Species/Group : Synthetic spinel

    Birefringence : none

    Dispersion : .020

    Hardness : 8

    Toughness : good

    Ultrasonic : Usually safe

    Steam : usually safe

    UV Long : Inert to strong

    UV Short : Inert to strong

    Pleochroism : None

    Strength : N/A

    Pleochroism [...]

  • Star Diopside

    Refractive Index : 1.701 – 1.675 (+0.029 – 0.010)

    Optical Characteristic : DR, B+,  AGG

    Specific Gravity : 3.29 (+0.11 – 0.07)

    Formula : CaMgSi2O6

    Crystal System : Monoclinic

    Variety/Species : Diopside

    Species/Group : Pyroxene group

    Birefringence : 0.024 to 0.030

    Dispersion : N/A

    Hardness : 5.5 to 6

    Toughness : poor

    Ultrasonic : risky

    Steam : Never

    UV Long : weak

    UV Short : Inert

    Pleochroism : 2 or [...]

  • Star Beryl

    Refractive Index : 1.583 – 1.577 (+0.017 – 0.017)

    Optical Characteristic : DR, U-

    Specific Gravity : 2.72 (+0.18 – 0.05)

    Formula : Be3Al2Si6O18

    Crystal System : Hexagonal

    Variety/Species : Star Beryl

    Species/Group : Beryl

    Birefringence : 0.005 – 0.009

    Dispersion : 0.014

    Hardness : 7.5 to 8

    Toughness : good

    Ultrasonic : risky

    Steam : risky

    UV Long : Inert

    UV Short : Inert

    Pleochroism : 2 colors

    Strength : [...]

  • Star Enstatite

    Refractive Index : 1.673 – 1.663 (+0.010 – 0.010)

    Optical Characteristic : DR, B+

    Specific Gravity : 3.25 (+0.15 – 0.02)

    Formula : MgSiO3

    Crystal System : Orthorhombic

    Variety/Species : Enstatite

    Species/Group : Pyroxene group

    Birefringence : 0.008 to 0.011

    Dispersion : none

    Hardness : 5 to 6

    Toughness : poor

    Ultrasonic : risky

    Steam : Never

    UV Long : Inert

    UV Short : Inert

    Pleochroism : 2 or 3 [...]

  • Star Ruby

    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 : Ruby

    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 [...]

  • 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 [...]

  • Star spinel

    Refractive Index : 1.718 (+0.017 – 0.008)

    Optical Characteristic : SR

    Specific Gravity : 3.60 (+0.10 – 0.03)

    Formula : MgAI2O4

    Crystal System : Cubic

    Variety/Species : spinel

    Species/Group : Spinel Group

    Birefringence : none

    Dispersion : 0.020

    Hardness : 8

    Toughness : good

    Ultrasonic : Usually safe

    Steam : usually safe

    UV Long : Inert to strong

    UV Short : Inert to weak

    Pleochroism : None

    Strength : N/A

    Pleochroism Colors [...]

  • Tourmaline Group

    Refractive Index : 1.644 – 1.624 + 0.134 – 0.021

    Optical Characteristic : DR U-

    Specific Gravity : 3.06 + 0.20 – 0.06

    Formula : Na(Li,AI)3AI6(BO3)3Si6018(OH)4

    Crystal System : Trigonal

    Variety/Species : All

    Species/Group : Tourmaline Group

    Birefringence : 0.018 to 0.040

    Dispersion : 0.017

    Hardness : 7 to 7.5

    Toughness : Fair

    Ultrasonic : Risky

    Steam : Risky

    UV Long : Inert to weak

    UV Short : Inert [...]

  • Sphalerite

    Refractive Index : 2.50 – 2.369

    Optical Characteristic : SR

    Specific Gravity : 4.05 (+0.05 – 0.15)

    Formula : ZnS + Fe

    Crystal System : Cubic

    Variety/Species : Sphalerite

    Species/Group : sphalerite Group

    Birefringence : none

    Dispersion : 0.156

    Hardness : 3.5 to 4

    Toughness : poor

    Ultrasonic : Never

    Steam : Never

    UV Long : Inert to strong

    UV Short : Inert to strong

    Pleochroism : None

    Strength : N/A

    Pleochroism [...]