• ALEXANDRITE

    Green in sunlight. Red in the lamplight. Color-changing alexandrite is nature’s magic trick.

     

    • Mineral: Chrysoberyl
    • Chemistry: BeAl2O4
    • Color: Bluish green in daylight, purplish-red in incandescent light
    • Refractive Index: 1.746 to 1.755
    • Birefringence: 0.008 to 0.010
    • Specific Gravity: 3.73
    • Mohs Hardness: 8.5
  • AMBER

    Amber is nature’s time capsule. This fossilized tree resin contains remnants of life on earth millions of years ago.

     

    • Organic, not mineral: Fossilized resin
    • Chemistry: C10H16O
    • Color: Yellow, orange, and brown
    • Refractive index: 1.540
    • Specific gravity: 1.08
    • Mohs Hardness: 2.0 to 2.5
  • AMETHYST

    The essence of the color purple, amethyst is beautiful enough for crown jewels yet affordable enough for class rings.

     

    • Mineral: Chrysoberyl
    • Chemistry: BeAl2O4
    • Color: Bluish green in daylight, purplish-red in incandescent light
    • Refractive Index: 1.746 to 1.755
    • Birefringence: 0.008 to 0.010
    • Specific Gravity: 3.73
    • Mohs Hardness: 8.5
  • AMETRINE

    This transparent quartz has colors of both amethyst and citrine and is called ametrine or amethyst-citrine.

     

    • Mineral: Quartz
    • Chemical composition: SiO2
    • Color: Bicolor orange/yellow and purple
    • Refractive index: 1.544 to 1.553
    • Specific gravity: 2.66 (+0.03/-0.02)
    • Mohs hardness: 7
  • AQUAMARINE

    Named after seawater, aquamarine’s fresh watery hue is a cool plunge into a refreshing pool.

     

    • Mineral: Beryl
    • Chemistry: Be3Al2Si6O18
    • Color: greenish blue, light in tone
    • Refractive Index: 1.577 to 1.583
    • Birefringence: 0.005 to 0.009
    • Specific Gravity: 2.72
    • Mohs Hardness: 7.5 to 8.0
  • CITRINE

    Citrine is the transparent, pale yellow to brownish orange variety of quartz.

     

    • Mineral: Quartz
    • Chemical composition: SiO2
    • Color: Yellow to orange to orangy red
    • Refractive index: 1.544 to 1.553
    • Specific gravity: 2.66 (+0.03/-0.02)
    • Mohs hardness: 7
  • DIAMOND

    Diamonds are among nature’s most precious and beautiful creations.

     

    • Mineral: Diamond
    • Chemistry: C
    • Color: Colorless
    • Refractive Index: 2.42
    • Birefringence: None
    • Specific Gravity: 3.52 (+/-0.01)
    • Mohs Hardness: 10
  • EMERALD

    Emerald is the bluish-green to green variety of beryl, a mineral species that includes aquamarine.

     

    • Mineral: Beryl
    • Chemistry: Be3Al2Si6O18
    • Color: Vibrant green
    • Refractive Index: 1.577 to 1.583
    • Birefringence: 0.005 to 0.009
    • Specific Gravity: 2.72
    • Mohs Hardness: 7.5 to 8
  • FANCY COLOR DIAMOND

    Dazzling brilliance. Captivating color. The planet’s most valued gems are fancy color diamonds.

     

    • Mineral:   Diamond
    • Chemistry:   C
    • Color: All colors
    • Refractive index: 2.42
    • Birefringence: None
    • Specific gravity:   3.52
    • Mohs Hardness: 10
  • GARNET

    Garnets are a set of closely related minerals forming a group, with gemstones in almost every color.

     

    • Mineral: Garnet group
    • Chemistry:
      Almandine- Fe3Al2(SiO4)3
      Andradite- Ca3Fe2(SiO4)3
      Grossular- Ca3Al2(SiO4)3
      Pyrope- Mg3Al2(SiO4)3
      Rhodolite- (Mg, Fe)3Al2(SiO4)3
      Spessartine- Mn3Al2(SiO4)3
    • Color: All colors
    • Refractive index: 1.714-1.888
    • Birefringence: None
    • Specific gravity: 3.47-4.15
    • Mohs hardness: 6.5-7.5
  • IOLITE

    According to legend, Vikings used iolite slices to reduce glare when checking the sun’s position.

     

    • Mineral: Iolite (Cordierite)
    • Chemical composition: Mg2Al4Si5O18
    • Color: Violetish blue (pleochroic colorless-yellow)
    • Refractive index: 1.542 – 1.551
    • Birefringence: +0.045, -0.011
    • Specific gravity: 2.61
    • Maohs hardness: 7.0 – 7.5
  • JADE

    Jade is actually two separate gems: nephrite and jadeite. In China, a pierced jade disk is a symbol of heaven.

     

    • Mineral: Jadeite and Nephrite
    • Chemistry: NaAlSi2O6 and Ca2(Mg,Fe)5Si8O22(OH)2
    • Color:  Green, white, orange, yellow, lavender, black
    • Refractive index: 1.666 to 1.680 (+/-0.008) and 1.606 to 1.632 (+0.009, 0.006)
    • Birefringence:  Usually not detectable
    • Specific gravity: 3.34 and 2.95
    • Mohs Hardness: 6.5 to 7 and 6.0 to 6.5
  • KUNZITE

    Collectors love kunzite for its color range, from delicate pastel pink to intense violetish purple.

     

    • Mineral: Spodumene
    • Chemical composition: LiAlSi2O6
    • Color: Pink-violetish purple, light-intense
    • Refractive index: 1.660 to 1.676
    • Birefringence: 0.014 to 0.016
    • Specific gravity: 3.18
    • Mohs hardness: 6.5 to 7.0
  • LAPIS LAZULI

    Lapis is a beautiful rock; an aggregate of several minerals, mainly lazurite, calcite, and pyrite.

     

    • Mineral: Rock
    • Chemical composition: An aggregate
    • Color: Greenish blue to violetish blue
    • Refractive index: 1.500, sometimes 1.670
    • Birefringence: None
    • Specific gravity: 2.75 (+/- 0.25)
  • MOONSTONE

    A ghostly sheen moves under the surface of this feldspar, like moonlight glowing in the water.

     

    • Mineral: Feldspar
    • Chemistry:  KAlSi3O8
    • Color: Colorless to White, Gray, Green, Peach, Brown
    • Refractive index: 1.518 to 1.526
    • Birefringence: 0.05 to 0.008
    • Specific gravity: 2.58
    • Mohs Hardness: 6.0 to 6.5
  • RUBY

    Ruby is the most valuable variety of the corundum mineral species, which also includes sapphire.

     

    • Mineral: Corundum
    • Chemical composition: Al2O3
    • Color: Red
    • Refractive index: 1.762 to 1.770
    • Birefringence: 0.008 to 0.010
    • Specific gravity: 4.00 (+/- 0.05)
    • Mohs Hardness: 9
  • SAPPHIRE

    The name “sapphire” can also apply to any corundum that’s not ruby red, another corundum variety.

     

    • Mineral: Corundum
    • Chemistry: Al2O3
    • Color: Every color but red
    • Refractive index: 1.762 to 1.770
    • Birefringence: 0.008 to 0.010
    • Specific gravity: 4.00
    • Mohs Hardness: 9
  • SPINEL

    The Black Prince’s Ruby. The Timur Ruby. For centuries, spinel, the great imposter, masqueraded as ruby in Europe’s crown jewels.

     

    • Mineral:   spinel
    • Chemistry: MgAl2O4
    • Color: red, orange, pink, purple, blue, black
    • Refractive index: 1.718
    • Birefringence: none
    • Specific gravity: 3.60
    • Mohs Hardness: 8
  • SUNSTONE

    Sunstone’s phenomenal varieties show a distinct and lively glitter called aventurescence.

     

    • Mineral: Feldspar
    • Chemical composition:
      Orthoclase – KAlSi3O8
      Oligoclase and labradorite – solid solution between NaAlSi3O8 and CaAl2Si2O8
    • Color: Yellow, green, red, red-brown, colorless
    • Refractive Index:
      Orthoclase Sunstone – 1.518 to 1.526
      Oligoclase Sunstone – 1.537 to 1.547
      Labradorite Sunstone – 1.559 to 1.568
    • Birefringence:
      Orthoclase – 0.005 to 0.008
      Oligoclase and labradorite – 0.007 to 0.010
    • Specific gravity:
      Orthoclase – 2.58
      Oligoclase – 2.65
      Labradorite – 2.70
    • Mohs hardness: 6.0 – 7.2
  • TANZANITE

    Poised between lush blue, vibrant violet, and rich purple, exotic tanzanite is found in only one place on earth, near majestic Mount Kilimanjaro.

     

    • Mineral: Zoisite
    • Chemistry: Ca2Al3(SiO4)3(OH)
    • Color: Violet blue to bluish violet to violet purple
    • Refractive Index: 1.691 to 1.700
    • Birefringence: 0.008 to 0.013
    • Specific Gravity: 3.35
    • Mohs Hardness: 6 to 7
  • TOPAZ

    Honey yellow. Fiery orange. Cyclamen pink. Icy blue. In warm or cool tones, topaz is a lustrous and brilliant gem.

     

    • Mineral: Topaz
    • Chemistry: Al2(F,OH)2SiO4
    • Color: Yellow, orange, brown, pink to red to purple red, blue, light green, and colorless
    • Refractive index: 1.619 to 1.627
    • Birefringence: 0.008 to 0.010
    • Specific gravity: 3.53
    • Mohs Hardness: 8
  • TOURMALINE

    Tourmalines have a wide variety of exciting colors with one of the widest color ranges of any gem.

    • Mineral: Tourmaline
    • Chemistry:
      Elbaite Na(Li1.5,Al1.5)Al6Si6O18(BO3)3(OH)4
      Dravite NaMg3Al6Si6O18(BO3)3(OH)4
      Liddicoatite Ca(Li2Al)Al6Si6O18(BO3)3(OH)3F
      Chromedravite NaMg3Cr6Si6O18(BO3)3(OH)4
    • Color: All colors
    • Refractive index: 1.624 to 1.644
    • Birefringence: 0.018 to 0.040
    • Specific gravity: 3.06 (+0.20, -0.06)
    • Mohs Hardness: 7 to 7.5
  • TURQUOISE

    Azure sky, robin’s egg blue: Vivid shades of turquoise define the color that’s named after this gem.

     

    • Mineral: Turquoise
    • Chemistry: CuAl6(PO4)4  (OH)8.5H2O
    • Color: Blue to green
    • Refractive Index: 1.610 to 1.650
    • Birefringence: Not detectable
    • Specific Gravity: 2.76 (+0.14, -0.36)
    • Mohs Hardness: 5 to 6
  • ZIRCON

    Zircon is a colorful gem with high refraction and fire that’s unfairly confused with cubic zirconia.

    • Mineral: Zircon
    • Chemistry: ZrSiO4
    • Color: Blue, red, yellow, orange, brown, green
    • Refractive index:
    • High: 1.925 to 1.984 (+/- 0.040)
    • Medium: 1.875 to 1.905 (+/- 0.030)
    • Low: 1.810 to 1.815 (+/-0.030)
    • Birefringence: 0.000 to 0.059 (low to high)
    • Specific gravity: 3.90 to 4.73
    • Mohs Hardness: 6 to 7.5 (low to high)

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