Gemstone Refractive Index: The Definitive Guide

Gemstone Refractive Index: The Definitive GuideThis illustrated chart shows refractive index values for 155 natural gemstone varieties. It is the most complete and accurate refractive index scale for gemstones available online, and includes many rare varieties. 
 
 		 Gem
Variety		 Refractive
Index 		Double
Refraction
Hematite Hematite 2.940-3.220 0.287
Cinnabar Cinnabar 2.905-3.256 0.351
Cuprite Cuprite 2.849 none
Natural Diamond Diamond 2.417-2.419 none
Sphalerite Sphalerite 2.368-2.371 none 
Cassiterite Cassiterite 1.997-2.098  0.096-0.098
Scheelite Scheelite 1.918-1.937  0.010-0.018
Demantoid Garnet Demantoid
Garnet		 1.88-1.94  none
Uvarovite Garnet Uvarovite
Garnet		 1.865 none
Sphene (Titanite) Sphene 
(Titanite)		 1.843-2.110 0.100-0.192
Zircon Zircon 1.810-2.024 0.002-0.059
Cerussite Cerussite 1.804-2.079 0.274
Spessartite Garnet Spessartite
Garnet		 1.790-1.820 none
Painite Painite 1.787-1.816 0.029
Almandine Garnet Almandine 
Garnet		 1.770-1.820 none
Natural Ruby Ruby 1.762-1.778 0.008 
Star Ruby Star Ruby 1.762-1.778 0.008 
Sapphire Sapphire 1.762-1.778 0.008
Star Sapphire Star
Sapphire		 1.762-1.778 0.008 
Mali Garnet Mali Garnet 1.760-1.780 none
Benitoite Benitoite 1.757-1.804 0.047
Color Change Alexandrite Alexandrite 1.746-1.763 0.007-0.011
Alexandite Cat's Eye Alexandrite
Cat's Eye		 1.746-1.763 0.007-0.011
Chrysoberyl Chrysoberyl 1.746-1.763 0.007-0.011 
Chrysoberyl Cat's Eye Chrysoberyl
Cat's Eye		 1.746-1.763 0.007-0.011 
Vanadium Chrysoberyl Vanadium
Chrysoberyl		 1.746-1.763 0.007-0.011 
Rhodolite Garnet Rhodolite
Garnet		 1.742-1.785 none
Color Change Garnet Color-Change 
Garnet		 1.742-1.780 none
Malaia Garnet Malaia Garnet 1.742-1.780 none
Grossular Garnet Grossular
Garnet		 1.734-1.759 none
Tsavorite Garnet Tsavorite
Garnet		 1.734-1.759 none
Leuco Garnet Leuco Garnet 1.734-1.759 none
Hessonite Garnet Hessonite
Garnet		 1.730-1.757 none
Epidote Epidote 1.729-1.768 0.015-0.049
Bastnasite Bastnasite 1.720-1.820 0.100
Azurite Azurite 1.720-1.848 0.108-0.110
Pyrope Garnet Pyrope
Garnet		 1.720-1.756  none
Taaffeite Taaffeite 1.719-1.730 0.004-0.009
Rhodonite Rhodonite 1.716-1.752 0.010-0.014
Spinel Spinel 1.712-1.782  none
Kyanite Kyanite 1.710-1.734 0.015-0.033
Diaspore Diaspore 1.702-1.750 0.048
Serendibite Serendibite 1.701-1.743 0.005
Idocrase (Vesuvianite) Idocrase 
(Vesuvianite)		 1.700-1.723  0.002-0.012
Tanzanite Tanzanite 1.691-1.700 0.009
Zoisite Zoisite 1.691-1.700 0.009
Dumortierite Dumortierite 1.678-1.689 0.015-0.037
Sinhalite Sinhalite 1.665-1.712 0.036-0.042
Chrome Diopside Chrome
Diopside		 1.664-1.730 0.024-0.031
Diopside Diopside 1.664-1.730 0.024-0.031
Kornerupine Kornerupine 1.660-1.699 0.012-0.017
Hiddenite Hiddenite 1.660-1.681 0.014-0.016
Kunzite Kunzite 1.660-1.681 0.014-0.016
Spodumene Spodumene 1.660-1.681 0.014-0.016
Axinite Axinite 1.656-1.704 0.010-0.012
Malachite Malachite 1.666-1.909 0.254
Sillimanite Sillimanite 1.655-1.684 0.014-0.021
Jadeite Jade Jadeite Jade 1.652-1.688 0.020
Peridot Peridot 1.650-1.703 0.036-0.038
Enstatite Enstatite 1.650-1.680 0.009-0.012
Euclase Euclase 1.650-1.677 0.019-0.025
Phenakite Phenakite 1.650-1.670 0.016
Dioptase Dioptase 1.644-1.709 0.051-0.053
Jet Jet 1.640-1.680 none
Jeremejevite Jeremejevite 1.637-1.653 0.007-0.013
Barite Barite 1.636-1.648 0.012
Danburite Danburite 1.630-1.636 0.006-0.008
Clinohumite Clinohumite 1.629-1.674 0.028-0.041
Apatite Apatite 1.628-1.649 0.002-0.006
Cat's Eye Apatite Cat's Eye
Apatite		 1.628-1.649 0.002-0.006
Andalusite Andalusite 1.627-1.649 0.007-0.013
Smithsonite Smithsonite 1.621-1.849 0.228
Datolite Datolite 1.621-1.675 0.040-0.060
Celestine Celestine 1.619-1.635 0.010-0.012
Chrome Tourmaline Chrome 
Tourmaline		 1.614-1.666 0.014-0.032
Paraiba Tourmaline Paraiba 
Tourmaline		 1.614-1.666 0.014-0.032
Rubellite Tourmaline Rubellite 
Tourmaline		 1.614-1.666 0.014-0.032
Tourmaline Tourmaline 1.614-1.666 0.014-0.032
Actinolite Actinolite 1.614-1.653 0.020-0.025
Hemimorphite Hemimorphite 1.614-1.638 0.022
Prehnite Prehnite 1.611-1.669 0.021-0.039
Gaspeite Gaspeite 1.610-1.810 0.22
Turquoise Turquoise 1.610-1.650 0.040
Topaz Topaz 1.609-1.643  0.009-0.016
Imperial Topaz Imperial
Topaz		 1.609-1.643  0.009-0.016 
Sugilite Sugilite 1.607-1.611 0.001-0.004
Brazilianite Brazilianite 1.602-1.623 0.019-0.021
Pezzotaite Pezzotaite 1.601-1.620 0.008-0.011
Rhodochrosite Rhodochrosite 1.600-1.820 0.208-0.220
Nephrite Jade Nephrite Jade 1.600-1.627 0.027
Larimar Larimar 1.595-1.645 0.038
Eudialyte Eudialyte 1.591-1.633 0.003-0.010
Grandidierite Grandidierite 1,590-1.623 0.033
Howlite Howlite 1.586-1.605 0.019
Amblygonite Amblygonite 1.578-1.646 0.024-0.030
Emerald Emerald 1.565-1.602 0.005
Aquamarine Aquamarine 1.565-1.602 0.005
Morganite Morganite 1.562-1.605  0.004-0.010
Goshenite Beryl Goshenite
Beryl		 1.562-1.605 0.004-0.010 
Golden Beryl Golden Beryl 1.562-1.605 0.004-0.010  
Red Beryl Red Beryl
(Bixbite)		 1.562-1.605 0.004-0.010 
Labradorite Labradorite 1.559-1.570 0.008-0.010
Hambergite Hambergite 1.553-1.628  0.072
Charoite Charoite 1.550-1.561 0.004-0.009
Amethyst Amethyst 1.544-1.553 0.009 
Aventurine Aventurine 1.544-1.553  0.009
Ametrine Ametrine 1.544-1.553 0.009 
Citrine Citrine 1.544-1.553 0.009 
Gem Silica Gem Silica 1.544-1.553 0.009 
Rock Crystal Rock Crystal 1.544-1.553 0.009 
Rose Quartz Rose
Quartz		 1.544-1.553 0.009 
Smoky Quartz Smoky
Quartz		 1.544-1.553 0.009 
Andesine Andesine 1.543-1.551 0.009
Iolite Iolite 1.542-1.578 0.008-0.012
Scapolite Scapolite 1.540-1.579 0.009-0.037
Jasper Jasper 1.54 none
Amber Amber 1.539-1.545 none
Oligoclase Oligoclase 1.538-1.550 0.007-0.013
Aragonite Aragonite 1.530-1.685 0.155
Williamsite Williamsite 1.530-1.575 0.001-0.002
Agate Agate 1.530-1.540 0.004-0.009
Bloodstone Bloodstone 1.530-1.540 0.004-0.009
Chalcedony Chalcedony 1.530-1.540 0.004-0.009
Chrome Chalcedony Chrome 
Chalcedony		 1.530-1.540 0.004-0.009
Carnelian Carnelian 1.530-1.540 0.004-0.009
Chrysoprase Chrysoprase 1.530-1.540 0.004-0.009
Onyx Onyx 1.530-1.540 0.004-0.009
Lepidolite Lepidolite 1.525-1.587 0.013
Sunstone Sunstone 1.525-1.548 0.010
Amazonite Amazonite 1.522-1.530 0.008
Pearl Pearl 1.52-1.69 0.158
Ammolite Ammolite
(Korite)		 1.52-1.68 0.155
Orthoclase Orthoclase 1.518-1.530 0.008
Moonstone Moonstone 1.518-1.528 0.008
Carletonite Carletonite 1.517-1.521 0.004
Poudretteite Poudretteite 1.511-1.532 0.021
Petalite Petalite 1.502-1.518 0.012-0.017
Lapis Lazuli Lapis Lazuli 1.50 none
Hauyne Hauyne 1.498-1.510 none
Ulexite Ulexite 1.491-1.520 0.029
Calcite Calcite 1.486-1.658 0.172
Cobaltoalcite Cobaltoalcite 1.486-1.658 0.172
Coral Coral 1.486-1.658 0.160-0.172
Moldavite Moldavite 1.48-1.54 none
Hackmanite Hackmanite 1.48 none
Sodalite Sodalite 1.48 none
Chrysocolla Chrysocolla 1.46-1.57 0.023-0.040
Obsidian Obsidian 1.45-1.55 none
Fluorite Fluorite 1.434 none
Mexican Fire Opal Mexican 
Fire Opal		 1.37-1.52 none
Opal Opal 1.37-1.52 none
  

Refractive Indices and Double Refraction Values

The following table organizes gemstones from highest to lowest refractive indices.

Gemstone Refractive Index Double Refraction
Hematite 2.940-3.220 0.287
Cinnabar 2.905-3.256 0.351
Proustite 2.881-3.084 0.203
Pyrargyrite 2.880-3.080 0.200
Cuprite 2.849 none
Rutile 2.616-2.903 0.287
Brookite 2.583-2.700 0.117
Anatase 2.488-2.564 0.046-0.067
Diamond 2.417-2.419 anomalous
Fabulite 2.409 none
Stibiotantalite 2.370-2.450 0.080
Sphalerite 2.368-2.371 none
Crocoite 2.290-2.660 0.270
Wulfenite 2.280-2.400 0.120
Tantalite 2.260-2.430 0.160
Linobate 2.210-2.300 0.090
Manganotantalite 2.190-2.340 0.150
Cubic zirconia (CZ) 2.150-2.180 none
Mimetite 2.120-2.135 0.015
Phosgenite 2.114-2.145 0.028
Senarmontite 2.087 none
Boleite 2.030-2.050 0.020
Zincite 2.013-2.029 0.016
Cassiterite 1.997-2.098 0.096-0.098
Simpsonite 1.994-2.040 0.058
Gadolinium gallium garnet (GGG) 1.970-2.020 0.058
Sulfur 1.958-2.245 0.291
Bayldonite 1.950-1.990 0.04
Scheelite 1.918-1.937 0.010-0.018
Andradite garnet 1.880-1.940 none
Anglesite 1.878-1.895 0.017
Uvarovite garnet 1.865 none
Purpurite 1.850-1.920 0.007
Sphene (titanite) 1.843-2.110 0.100-0.192
Yttrium aluminum garnet (YAG) 1.833-1.835 none
Zircon 1.810-2.024 0.002-0.059
Cerussite 1.804-2.079 0.274
Gahnite 1.791-1.818 none
Spessartite garnet 1.790-1.820 none
Painite 1.787-1.816 0.029
Monazite 1.774-1.849 0.049-0.055
Almandine garnet 1.770-1.820 none
Gadolinite 1.770-1.820 0.01-0.04
Ruby (corundum) 1.762-1.778 0.008
Sapphire (corundum) 1.762-1.778 0.008
Benitoite 1.757-1.804 0.047
Shattuckite 1.752-1.815 0.063
Chrysoberyl 1.746-1.763 0.007-0.011
Periclase 1.740 none
Scorodite 1.738-1.816 0.027-0.030
Staurolite 1.736-1.762 0.010-0.015
Grossular garnet 1.734-1.759 none
Chambersite 1.732-1.744 0.012
Hessonite garnet 1.730-1.757 none
Epidote 1.729-1.768 0.015-0.049
Pyroxmangite 1.726-1.764 0.016-0.020
Azurite 1.720-1.848 0.108-0.110
Pyrope garnet 1.720-1.756 none
Hodgkinsonite 1.719-1.748 0.022-0.026
Taaffeite 1.719-1.730 0.004-0.009
Rhodonite 1.716-1.752 0.010-0.014
Gahnospinel 1.715-1.754 none
Spinel 1.712-1.762 none
Kyanite 1.710-1.734 0.015-0.033
Adamite 1.708-1.760 0.048-0.050
Diaspore 1.702-1.750 0.048
Serendibite 1.701-1.743 0.005
Sapphirine 1.701-1.734 0.004-0.007
Aegirine-augite 1.700-1.800 0.030-0.050
Idocrase (vesuvianite) 1.700-1.723 0.002-0.012
Tanzanite 1.691-1.700 0.009
Neptunite 1.690-1.736 0.029-0.045
Willemite 1.690-1.723 0.028-0.033
Rhodizite 1.690 none
Triphylite 1.689-1.702 0.006-0.008
Lithiophilite 1.680-1.700 0.01
Dumortierite 1.678-1.689 0.015-0.037
Legrandite 1.675-1.740 0.060
Hypersthene 1.673-1.731 0.010-0.016
Parisite 1.671-1.772 0.081-0.101
Clinozoisite 1.670-1.734 0.010
Sinhalite 1.665-1.712 0.036-0.042
Lawsonite 1.665-1.686 0.019-0.021
Diopside 1.664-1.730 0.024-0.031
Bustamite 1.662-1.707 0.014-0.015
Kornerupine 1.660-1.699 0.012-0.017
Hiddenite 1.660-1.681 0.014-0.016
Kunzite 1.660-1.681 0.014-0.016
Boracite 1.658-1.673 0.010-0.011
Axinite 1.656-1.704 0.010-0.012
Malachite 1.655-1.909 0.254
Sillimanite 1.655-1.684 0.014-0.021
Jadeite 1.652-1.688 0.20
Peridot 1.650-1.703 0.036-0.038
Ludlamite 1.650-1.697 0.038-0.044
Enstatite 1.650-1.680 0.009-0.012
Euclase 1.650-1.677 0.019-0.025
Phenakite 1.650-1.670 0.016
Dioptase 1.644-1.709 0.051-0.053
Jet 1.640-1.680 none
Eosphorite 1.638-1.671 0.028-0.035
Spurrite 1.637-1.681 0.039-0.040
Jeremejevite 1.637-1.653 0.007-0.013
Barite 1.636-1.648 0.012
Siderite 1.633-1.875 0.242
Danburite 1.630-1.636 0.006-0.008
Clinohumite 1.629-1.674 0.028-0.041
Apatite 1.628-1.649 0.002-0.006
Andalusite 1.627-1.649 0.007-0.013
Friedelite 1.625-1.664 0.030
Smithsonite 1.621-1.849 0.228
Datolite 1.621-1.675 0.040-0.050
Celestite 1.619-1.635 0.010-0.012
Tourmaline 1.614-1.666 0.014-0.032
Actinolite 1.614-1.653 0.020-0.025
Hemimorphite 1.614-1.636 0.022
Lazulite 1.612-1.646 0.031-0.036
Prehnite 1.611-1.669 0.021-0.039
Gaspéite 1.610-1.810 0.22
Turquoise 1.610-1.650 0.040
Topaz 1.609-1.643 0.008-0.016
Sugilite 1.607-1.611 0.001-0.004
Sogdianite 1.606-1.608 0.002
Brazilianite 1.602-1.623 0.019-0.021
Rhodochrosite 1.600-1.820 0.208-0.220
Odontolite 1.600-1.640 0.010
Nephrite 1.600-1.627 0.027
Pectolite (larimar) 1.595-1.645 0.038
Montebrasite 1.594-1.633 0.22
Phosphophyllite 1.594-1.621 0.021-0.033
Meliphanite 1.593-1.612 0.019
Eudialyte 1.591-1.633 0.003-0.010
Chondrodite 1.592-1.646 0.028-0.034
Catapleiite 1.590-1.629 0.039
Wardite 1.590-1.599 0.009
Herderite 1.587-1.627 0.023-0.032
Colemanite 1.586-1.615 0.028-0.030
Howlite 1.586-1.605 0.019
Zektzerite 1.582-1.585 0.003
Amblygonite 1.578-1.646 0.024-0.030
Ekanite 1.572-1.573 0.001
Anhydrite 1.570-1.614 0.044
Augelite 1.570-1.590 0.014-0.020
Emerald (beryl) 1.565-1.602 0.006
Aquamarine (beryl) 1.564-1.596 0.004-0.005
Variscite 1.563-1.594 0.031
Beryl (precious) 1.562-1.602 0.004-0.010
Tremolite 1.560-1.643 0.017-0.027
Vivianite 1.560-1.640 0.050-0.075
Serpentine 1.560-1.571 0.008-0.014
Larbradorite 1.559-1.570 0.008-0.010
Hambergite 1.553-1.628 0.072
Pyrophyllite 1.552-1.600 0.048
Muscovite 1.552-1.618 0.036-0.043
Beryllonite 1.552-1.561 0.009
Charoite 1.550-1.561 0.004-0.009
Amethyst (quartz) 1.544-1.553 0.009
Aventurine (quartz) 1.544-1.553 0.009
Rose quartz 1.544-1.553 0.009
Citrine (quartz) 1.544-1.553 0.009
Prasiolite (quartz) 1.544-1.553 0.009
Smoky quartz 1.544-1.553 0.009
Rock crystal (quartz) 1.544-1.553 0.009
Andesine 1.543-1.551 0.008
Oligoclase 1.542-1.549 0.007
Talc 1.540-1.590 0.050
Scapolite 1.540-1.579 0.006-0.037
Petrified Wood 1.540 none
Jasper 1.540 none
Amber 1.539-1.545 none
Ivory 1.535-1.570 none
Apophyllite 1.535-1.537 0.002
Tiger's eye 1.534-1.540 none
Aragonite 1.530-1.685 0.155
Agate 1.530-1.540 0.004-0.009
Chalcedony 1.530-1.540 0.004-0.009
Chrysoprase 1.530-1.540 0.004-0.009
Moss agate 1.530-1.540 0.004-0.009
Sepiolite 1.530 none
Witherite 1.529-1.677 0.148
Milarite 1.529-1.551 0.003
Nepheline 1.526-1.546 0.0004
Sunstone 1.525-1.548 0.01
Cordierite 1.522-1.578 0.008-0.018
Iolite (cordierite) 1.522-1.578 0.008-0.018
Amazonite 1.522-1.530 0.008
Pearl 1.520-1.690 0.156
Ammolite 1.520-1.680 0.155
Strontianite 1.520-1.670 0.150
Gypsum 1.520-1.529 0.009
Orthoclase 1.518-1.530 0.008
Sanidine 1.518-1.530 0.008
Moonstone 1.518-1.526 0.008
Pollucite 1.517-1.525 none
Carletonite 1.517-1.521 0.004
Stichtite 1.516-1.544 0.026
Thomsonite 1.515-1.542 0.006-0.025
Magnesite 1.509-1.717 0.022
Scolecite 1.509-1.525 0.007-0.012
Leucite 1.504-1.509 0.001
Mesolite 1.504-1.508 0.001
Dolomite 1.502-1.698 0.185
Petalite 1.502-1.519 0.012-0.017
Lapis lazuli 1.500 none
Haüyne 1.496-1.510 none
Tugtupite 1.496-1.502 0.006
Cancrinite 1.495-1.528 0.024-0.029
Celluloid 1.495-1.520 none
Ulexite 1.491-1.520 0.029
Yugawaralite 1.490-1.509 0.011-0.014
Whewellite 1.489-1.651 0.159-0.163
Kurnakovite 1.488-1.525 0.036
Inderite 1.486-1.507 0.017-0.020
Calcite 1.486-1.658 0.172
Coral 1.486-1.658 0.160-0.172
Moldavite 1.48-1.540 none
Natrolite 1.480-1.493 0.013
Sodalite 1.480 none
Analcime 1.479-1.489 none
Thaumasite 1.464-1.507 0.036
Creedite 1.461-1.485 0.024
Chrysocolla 1.460-1.570 0.023-0.040
Obsidian 1.450-1.550 none
Gaylussite 1.443-1.523 0.080
Glass 1.440-1.900 none
Fluorite 1.434 none
Sellaite 1.378-1.390 0.012
Opal 1.370-1.520 none
Villiaumite 1.327 anomalous

Notes

A double refraction of "none" means the stone is either isometric or amorphous. "Anomalous" means this singly refractive stone may show anomalous double refraction (ADR). Singly refractive gems with high refractive indices may show ADR.