Gemstone Reference Database

Searchable physical and optical property data for 130 gemstone species. Filter by refractive index, specific gravity, crystal system, and more. All data is sourced from GIA and standard gemological references.

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130 of 130 gems

Name RI Range SG Hardness Crystal System Optic Character Color
Agate 1.530–1.543 2.61 6.5–7 Trigonal Aggregate Multi, Colorless, Red Pink, Yellow Orange, Brown, Blue Violet, Black
Alexandrite 1.746–1.755 3.73 8.5 Orthorhombic Biaxial (+) Color Change, Green, Red Pink
Almandine Garnet 1.770–1.830 4.05 7–7.5 Cubic SR Red Pink, Purple, Brown
Amazonite 1.514–1.530 2.56 6–6.5 Triclinic Biaxial (−) Green, Blue Violet
Amber 1.539–1.545 1.08 2–2.5 Amorphous SR Yellow Orange, Brown, Red Pink, Green, Blue Violet
Amethyst 1.544–1.553 2.65 7 Trigonal Uniaxial (+) Purple, Blue Violet
Ametrine 1.544–1.553 2.65 7 Trigonal Uniaxial (+) Purple, Yellow Orange
Andalusite 1.629–1.649 3.17 7–7.5 Orthorhombic Biaxial (−) Green, Brown, Yellow Orange
Apatite 1.628–1.649 3.20 5 Hexagonal Uniaxial (−) Blue Violet, Green, Yellow Orange, Colorless
Aquamarine 1.577–1.583 2.72 7.5–8 Hexagonal Uniaxial (−) Blue Violet, Green
Aventurine 1.544–1.553 2.65 7 Trigonal Aggregate Green, Blue Violet, Red Pink, Yellow Orange, Brown
Benitoite 1.757–1.804 3.66 6–6.5 Hexagonal Uniaxial (+) Blue Violet
Black Opal 1.440–1.460 2.10 5.5–6.5 Amorphous SR Black
Black Spinel 1.712–1.730 3.60 8 Cubic SR Black
Bloodstone 1.530–1.543 2.61 6.5–7 Trigonal Aggregate Green, Multi
Blue Diamond 2.417 3.52 10 Cubic SR Blue Violet
Brown Diamond 2.417 3.52 10 Cubic SR Brown
Carnelian 1.530–1.543 2.61 6.5–7 Trigonal Aggregate Red Pink, Yellow Orange
Cassiterite 2.010–2.100 6.95 6–7 Tetragonal Uniaxial (+) Brown, Black, Yellow Orange
Cat's Eye Chrysoberyl 1.746–1.755 3.73 8.5 Orthorhombic Biaxial (+) Yellow Orange, Green, Brown
Chalcedony 1.530–1.543 2.61 6.5–7 Trigonal Aggregate Colorless, Blue Violet, Brown, Multi
Charoite 1.550–1.559 2.60 5–6 Monoclinic Aggregate Purple
Chrome Diopside 1.664–1.730 3.30 5.5–6.5 Monoclinic Biaxial (−) Green
Chrome Tourmaline 1.624–1.660 3.10 7–7.5 Trigonal Uniaxial (−) Green
Chrysoberyl 1.746–1.755 3.73 8.5 Orthorhombic Biaxial (+) Yellow Orange, Green, Brown
Chrysocolla 1.460–1.630 2.20 2.5–7 Amorphous Aggregate Green, Blue Violet
Chrysoprase 1.530–1.543 2.61 6.5–7 Trigonal Aggregate Green
Cinnabar 2.905–3.256 8.10 2–2.5 Trigonal Uniaxial (+) Red Pink, Brown
Citrine 1.544–1.553 2.65 7 Trigonal Uniaxial (+) Yellow Orange, Brown
Clinohumite 1.625–1.675 3.21 6 Monoclinic Biaxial (+) Yellow Orange, Brown
Color-Change Garnet 1.740–1.765 3.72 7–7.5 Cubic SR Color Change, Blue Violet, Green, Red Pink, Purple
Color-Change Sapphire 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Blue Violet, Purple, Color Change
Coral 1.486–1.658 2.68 3–4 Aggregate Aggregate Red Pink, Colorless, Black, Blue Violet
Cubic Zirconia 2.150–2.180 5.80 8–8.5 Cubic SR Colorless, Red Pink, Blue Violet, Green, Yellow Orange, Brown, Purple, Black
Cuprite 2.849 6.14 3.5–4 Cubic SR Red Pink, Brown
Danburite 1.627–1.636 3.00 7–7.5 Orthorhombic Biaxial (−) Colorless, Yellow Orange, Red Pink
Demantoid Garnet 1.880–1.895 3.84 6.5–7 Cubic SR Green, Yellow Orange
Diamond 2.417 3.52 10 Cubic SR Colorless, Yellow Orange, Brown, Red Pink, Blue Violet, Green
Diaspore 1.685–1.752 3.35 6.5–7 Orthorhombic Biaxial (+) Color Change, Green, Yellow Orange, Red Pink
Emerald 1.565–1.602 2.72 7.5–8 Hexagonal Uniaxial (−) Green
Enstatite 1.663–1.673 3.27 5–5.5 Orthorhombic Biaxial (+) Green
Fire Opal 1.370–1.470 2.00 5.5–6.5 Amorphous SR Yellow Orange, Red Pink
Fluorite 1.432–1.436 3.18 4 Cubic SR Purple, Blue Violet, Green, Yellow Orange, Colorless, Red Pink, Color Change
Goshenite 1.577–1.583 2.72 7.5–8 Hexagonal Uniaxial (−) Colorless
Grandidierite 1.590–1.623 2.95 7–7.5 Orthorhombic Biaxial (−) Blue Violet, Green
Green Tourmaline 1.616–1.650 3.06 7–7.5 Trigonal Uniaxial (−) Green
Grossular Garnet 1.734–1.759 3.61 6.5–7.5 Cubic SR Colorless, Green
Hackmanite 1.483–1.487 2.27 5.5–6 Cubic SR Colorless, Purple, Red Pink, Color Change
Hauyne 1.494–1.509 2.47 5.5–6 Cubic SR Blue Violet
Hawk's Eye 1.544–1.553 2.65 7 Trigonal Aggregate Blue Violet, Green
Heliodor 1.568–1.580 2.72 7.5–8 Hexagonal Uniaxial (−) Yellow Orange, Green
Hematite 2.940–3.220 5.28 5.5–6.5 Trigonal Uniaxial (−) Black
Hessonite Garnet 1.730–1.760 3.61 7–7.5 Cubic SR Yellow Orange, Brown, Green, Red Pink, Colorless
Hiddenite 1.660–1.676 3.18 6.5–7 Monoclinic Biaxial (+) Green
Howlite 1.583–1.608 2.53 3.5 Monoclinic Aggregate Colorless, Blue Violet
Indicolite 1.624–1.644 3.06 7–7.5 Trigonal Uniaxial (−) Blue Violet
Iolite 1.542–1.551 2.59 7–7.5 Orthorhombic Biaxial (−) Blue Violet, Purple
Ivory 1.535–1.540 1.85 2.5–3 Aggregate Aggregate Colorless, Yellow Orange, Brown
Jadeite 1.654–1.688 3.34 6.5–7 Aggregate Aggregate Green, Purple, Colorless, Black, Red Pink, Yellow Orange, Multi
Jet 1.640–1.680 1.32 2.5–4 Amorphous SR Black
Kornerupine 1.660–1.699 3.33 6.5 Orthorhombic Biaxial (−) Green, Brown, Yellow Orange
Kunzite 1.660–1.676 3.18 6.5–7 Monoclinic Biaxial (+) Red Pink, Purple
Kyanite 1.712–1.734 3.68 4.5–7 Triclinic Biaxial (−) Blue Violet, Colorless, Green
Labradorite 1.559–1.573 2.70 6–6.5 Triclinic Biaxial (−) Multi, Brown, Black, Blue Violet
Lapis Lazuli 1.500–1.670 2.75 5–6 Aggregate Aggregate Blue Violet
Larimar 1.595–1.640 2.80 4.5–5 Triclinic Biaxial (+) Blue Violet
Low-Type Zircon 1.780–1.815 4.00 6–7.5 Tetragonal SR Green, Brown, Yellow Orange
Malachite 1.655–1.909 3.80 3.5–4 Monoclinic Biaxial (−) Green
Malaya / Umbalite Garnet 1.730–1.780 3.75 7–7.5 Cubic SR Yellow Orange, Red Pink
Moissanite 2.648–2.691 3.22 9.25 Hexagonal Uniaxial (+) Colorless, Green, Yellow Orange, Blue Violet
Moldavite 1.480–1.510 2.35 5.5 Amorphous SR Green
Moonstone 1.518–1.526 2.58 6–6.5 Monoclinic Biaxial (−) Colorless, Yellow Orange, Brown, Green, Red Pink
Morganite 1.572–1.600 2.82 7.5–8 Hexagonal Uniaxial (−) Red Pink, Yellow Orange
Nephrite 1.600–1.627 2.95 6–6.5 Aggregate Aggregate Green, Colorless, Black, Brown
Obsidian 1.480–1.510 2.40 5–5.5 Amorphous SR Black, Brown, Green, Multi
Onyx 1.530–1.543 2.61 6.5–7 Trigonal Aggregate Black
Opal 1.370–1.470 2.15 5.5–6.5 Amorphous SR Colorless, Yellow Orange, Red Pink, Green, Blue Violet, Black, Multi
Padparadscha Sapphire 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Yellow Orange, Red Pink
Paraiba Tourmaline 1.624–1.644 3.06 7–7.5 Trigonal Uniaxial (−) Blue Violet, Green
Pearl 1.520–1.690 2.74 2.5–4.5 Aggregate Aggregate Colorless, Red Pink, Yellow Orange, Black, Brown, Green, Blue Violet
Peridot 1.654–1.690 3.34 6.5–7 Orthorhombic Biaxial (+) Green, Yellow Orange
Phenakite 1.654–1.670 2.96 7.5–8 Trigonal Uniaxial (+) Colorless
Pietersite 1.534–1.540 2.61 6.5–7 Aggregate Aggregate Multi, Blue Violet, Brown, Yellow Orange
Pink Diamond 2.417 3.52 10 Cubic SR Red Pink
Pink Sapphire 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Red Pink
Prasiolite 1.544–1.553 2.65 7 Trigonal Uniaxial (+) Green
Prehnite 1.611–1.665 2.88 6–6.5 Orthorhombic Biaxial (+) Green, Yellow Orange, Colorless
Pyrope Garnet 1.730–1.760 3.78 7–7.5 Cubic SR Red Pink
Rainbow Moonstone 1.559–1.572 2.70 6–6.5 Triclinic Biaxial (−) Colorless
Red Beryl 1.564–1.574 2.68 7.5–8 Hexagonal Uniaxial (−) Red Pink
Rhodochrosite 1.600–1.820 3.50 3.5–4 Trigonal Uniaxial (−) Red Pink
Rhodolite Garnet 1.740–1.770 3.84 7–7.5 Cubic SR Red Pink, Purple
Rhodonite 1.716–1.752 3.60 5.5–6.5 Triclinic Biaxial (+) Red Pink, Brown, Black
Rock Crystal 1.544–1.553 2.65 7 Trigonal Uniaxial (+) Colorless
Rose Quartz 1.544–1.553 2.65 7 Trigonal Uniaxial (+) Red Pink
Rubellite 1.624–1.644 3.06 7–7.5 Trigonal Uniaxial (−) Red Pink
Ruby 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Red Pink
Sapphire 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Blue Violet, Red Pink, Yellow Orange, Green, Colorless, Purple, Black, Color Change
Scapolite 1.540–1.572 2.63 6–6.5 Tetragonal Uniaxial (−) Colorless, Yellow Orange, Purple, Blue Violet
Serpentine 1.560–1.571 2.55 3–4 Monoclinic Aggregate Green, Yellow Orange, Brown, Colorless
Sinhalite 1.665–1.712 3.48 6.5–7 Orthorhombic Biaxial (−) Brown, Yellow Orange, Green
Smoky Quartz 1.544–1.553 2.65 7 Trigonal Uniaxial (+) Brown, Black
Sodalite 1.483–1.487 2.27 5.5–6 Cubic Aggregate Blue Violet, Colorless
Spessartite Garnet 1.790–1.815 4.15 7–7.5 Cubic SR Yellow Orange, Red Pink
Sphalerite 2.369–2.500 4.09 3.5–4 Cubic SR Yellow Orange, Brown, Red Pink, Green, Black
Sphene 1.843–2.110 3.53 5–5.5 Monoclinic Biaxial (+) Green, Yellow Orange, Brown
Spinel 1.712–1.736 3.60 7.5–8 Cubic SR Red Pink, Blue Violet, Purple, Black, Colorless, Green, Yellow Orange
Star Diopside 1.664–1.721 3.29 5–6 Monoclinic Biaxial (−) Black
Star Garnet 1.770–1.830 4.05 7–7.5 Cubic SR Red Pink, Purple, Brown
Star Ruby 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Red Pink
Star Sapphire 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Blue Violet, Black, Colorless, Purple, Red Pink, Yellow Orange
Sugilite 1.607–1.610 2.76 5.5–6.5 Hexagonal Uniaxial (−) Purple
Sunstone 1.537–1.572 2.63 6–6.5 Triclinic Biaxial (−) Yellow Orange, Red Pink, Colorless, Green
Synthetic Color-Change Corundum 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Color Change, Blue Violet, Red Pink, Purple
Synthetic Spinel 1.725–1.728 3.61 8 Cubic SR Blue Violet, Red Pink, Colorless, Green, Yellow Orange
Taaffeite 1.719–1.723 3.61 8–8.5 Hexagonal Uniaxial (−) Colorless, Red Pink, Purple, Blue Violet, Green
Tanzanite 1.691–1.700 3.35 6–7 Orthorhombic Biaxial (+) Blue Violet, Purple
Thulite 1.691–1.704 3.20 6–7 Orthorhombic Biaxial (+) Red Pink
Tiger's Eye 1.544–1.553 2.65 7 Trigonal Aggregate Yellow Orange, Brown
Topaz 1.609–1.643 3.53 8 Orthorhombic Biaxial (+) Blue Violet, Yellow Orange, Red Pink, Brown, Colorless
Tourmaline 1.624–1.644 3.06 7–7.5 Trigonal Uniaxial (−) Red Pink, Green, Blue Violet, Yellow Orange, Brown, Black, Colorless, Multi
Tsavorite Garnet 1.730–1.760 3.61 7–7.5 Cubic SR Green
Turquoise 1.610–1.650 2.76 5–6 Triclinic Aggregate Blue Violet, Green
Variscite 1.560–1.590 2.52 3.5–4.5 Orthorhombic Biaxial (−) Green
Watermelon Tourmaline 1.616–1.650 3.06 7–7.5 Trigonal Uniaxial (−) Multi, Red Pink, Green
White Sapphire 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Colorless
YAG 1.833 4.55 8–8.5 Cubic SR Colorless, Yellow Orange, Green, Blue Violet, Red Pink
Yellow Diamond 2.417 3.52 10 Cubic SR Yellow Orange
Yellow Sapphire 1.762–1.770 4.00 9 Trigonal Uniaxial (−) Yellow Orange
Zircon 1.925–1.984 4.69 7.5 Tetragonal Uniaxial (+) Blue Violet, Brown, Green, Yellow Orange, Red Pink, Colorless

About This Reference Database

This table contains physical and optical property data for 130 gemstone species and varieties, compiled from GIA's gem encyclopedia, Webster & Read, Hurlbut & Kammerling, and other standard gemological references. Each entry includes refractive index range, specific gravity, Mohs hardness, crystal system, optic character, and color categories.

Use the filters above to narrow candidates during gem identification. Combine RI range with SG range to quickly isolate a short list of candidates. The "Has synthetic" filter is useful when assessing stones that may have lab-grown origin. Individual gem pages include full property profiles, key differentiators, simulant detection notes, and natural vs. synthetic test guidance.

For deeper property slices: Refractive Index Chart  ·  Specific Gravity Chart  ·  UV Fluorescence Chart  ·  Mohs Hardness Chart