Gemsdat

GEMMOLOGICAL TABLES

ISOTROPIC BIAXIAL UNIAXIAL

STONE n min n max nx min nx max ny min ny max nz min nz max ne min ne max no min no max Biref min Biref max dens min dens max

Actinolite 1.602 1.622 1.613 1.634 1.628 1.653 0.016 0.028 2.96 3.44

Adamite 1.708 1.742 1.734 1.768 1.758 1.773 0.031 0.050 4.3 4.7

Aegirine 1.720 1.778 1.757 1.839 0.037 0.061 3.5 3.6

Afghanite 1.529 1.538 1.523 1.530 0.006 0.008 2.51 2.65

Albite - plagioclase feldspar group 1.526 1.533 1.531 1.536 1.538 1.542 0.009 0.012 2.57 2.69

Allanite - epidote group 1.640 1.791 1.650 1.815 1.660 1.828 0.013 0.036 3.4 4.2

Almandine - garnet group 1.785 1.830 3.95 4.3

Almandine-spessartine - garnet group 1.810 1.820 4.12 4.25

Amber 1.539 1.545 1 1.1

Amblygonite - amblygonite group 1.576 1.591 1.592 1.605 1.596 1.613 0.020 0.030 3.04 3.11

Ammolite -Korite- 1.520 1.525 1.671 1.674 1.665 1.680 0.135 0.155 2.6 2.85

Analcime 1.479 1.493 1.480 1.494 0.001 0.001 2.2 2.29

Anapaite 1.602 1.602 1.613 1.613 1.649 1.649 0.047 0.047 2.79 2.82

Anatase 2.488 2.497 2.534 2.564 0.046 0.073 3.79 3.97

Andalusite 1.628 1.646 1.638 1.653 1.638 1.654 0.007 0.013 3.05 3.2

Andalusite viridine 1.660 1.660 1.689 1.689 0.028 0.030 3.05 3.2

Andesine - plagioclase feldspar group 1.543 1.556 1.548 1.548 1.551 1.563 0.008 0.009 2.65 2.72

Andesine red - plagioclase feldspar group 1.551 1.554 1.560 1.562 0.008 0.009 2.67 2.69

Andradite - garnet group 1.870 1.935 3.82 3.94

Andradite-grossular -garnet group 1.758 1.785 3.63 3.72

Anglesite 1.877 1.877 1.882 1.882 1.894 1.894 0.017 0.017 6.3 6.39

Anhydrite 1.567 1.574 1.574 1.579 1.609 1.618 0.042 0.046 2.9 2.98

Anorthite - plagioclase feldspar group 1.573 1.577 1.580 1.585 1.585 1.590 0.013 0.013 2.75 2.77

Antigorite -bowenite- serpentine group 1.555 1.567 1.560 1.570 1.560 1.573 0.005 0.016 2.5 2.67

Anyolite - zoisite group 1.690 1.690 1.702 1.702 0.010 0.010 3.09 3.11

Apatite 1.628 1.653 1.629 1.658 0.001 0.007 3.1 3.35

Apophyllite 1.530 1.540 1.530 1.540 0.001 0.004 2.3 2.5

Aragonite 1.530 1.530 1.681 1.681 1.685 1.685 0.154 0.157 2.93 3

Augelite 1.574 1.575 1.576 1.576 1.588 1.590 0.014 0.015 2.7 2.75

Augite 1.671 1.735 1.672 1.741 1.703 1.774 0.026 0.039 3.19 3.56

Aurichalcite 1.654 1.661 1.740 1.749 1.743 1.756 0.089 0.095 3.64 4.23

Austinite 1.759 1.759 1.763 1.763 1.783 1.783 0.024 0.024 4.13 4.31

Aventurine quartz - crypto-crystalline quartz 1.539 1.553 1.530 1.535 0.004 0.009 2.58 2.91

Axinite -axinite group 1.656 1.693 1.660 1.681 1.668 1.704 0.009 0.012 3.17 3.36

Azurite 1.730 1.730 1.754 1.758 1.828 1.840 0.108 0.110 3.7 3.9

Baddeleyite 2.130 2.130 2.200 2.200 0.070 0.070 5.4 6.07

Bahianite 1.810 1.810 1.870 1.870 1.920 1.920 0.110 0.110 4.89 5.16

Bakelite artificial product 1.500 1.700 1.25 1.9

Barite 1.632 1.636 1.637 1.637 1.648 1.650 0.010 0.018 4.3 4.6

Barium sulfate - Artificial product 1.500 1.580 2.26 2.34

Bastnäsite 1.818 1.820 1.717 1.722 0.100 0.101 4.78 5.2

Benitoite 1.802 1.805 1.756 1.757 0.043 0.047 3.61 3.8

Beryl 1.558 1.599 1.567 1.610 0.004 0.010 2.6 2.97

Beryl-Aquamarine 1.562 1.583 1.572 1.590 0.005 0.008 2.66 2.8

Beryl-Emerald 1.558 1.593 1.576 1.602 0.004 0.010 2.62 2.8

Beryl-emerald synthetic -flux 1.553 1.565 1.557 1.569 0.003 0.005 2.62 2.7

Beryl-Goshenite 1.566 1.594 1.572 1.602 0.004 0.008 2.6 2.9

Beryl-Heliodor 1.562 1.595 1.568 1.602 0.004 0.008 2.6 2.9

Beryllonite 1.550 1.552 1.558 1.558 1.561 1.561 0.009 0.011 2.77 2.85

Beryl-Maxixe Beryl 1.580 1.584 1.588 1.592 0.008 0.008 2.6 2.8

Beryl-Morganite 1.572 1.592 1.578 1.600 0.008 0.009 2.71 2.9

Beryl-Red Beryl 1.561 1.568 1.568 1.577 0.004 0.008 2.65 2.87

Beryl-Synthetic - hydrothermally grown 1.563 1.610 1.569 1.620 0.004 0.010 2.64 2.73

Black coral 1.560 1.570 1.32 1.49

Boleite 2.030 2.030 2.050 2.050 0.020 0.020 4.8 5.1

Bone 1.540 1.570 1.98 2.01

Boracite 1.658 1.662 1.662 1.667 1.668 1.673 0.010 0.011 2.86 3.1

Brazilianite 1.599 1.603 1.609 1.610 1.620 1.623 0.019 0.021 2.9 3

Bronzite - enstatite group 1.665 1.686 1.680 1.703 0.015 0.017 3.3 3.43

Brookite 2.583 2.583 2.700 2.740 0.122 0.157 3.87 4.18

Brucite 1.580 1.600 1.559 1.590 0.010 0.020 2.38 2.41

Burbankite 1.597 1.623 1.616 1.636 0.013 0.019 3.5 3.58

Bustamite 1.640 1.695 1.651 1.708 1.653 1.710 0.014 0.015 3.32 3.43

Bytownite - plagioclase feldspar group 1.561 1.573 1.565 1.580 1.570 1.585 0.009 0.012 2.72 2.75

Calcite 1.486 1.550 1.658 1.740 0.172 0.190 2.71 2.94

Cancrinite 1.493 1.503 1.499 1.529 0.006 0.026 2.42 2.51

Carletonite 1.517 1.517 1.521 1.521 0.004 0.004 2.44 2.46

Casein -galalith- 1.530 1.560 1.32 1.34

Cassiterite 2.097 2.106 1.990 2.006 0.096 0.098 6.7 7.1

Catapleiite 1.582 1.603 1.600 1.639 0.018 0.039 2.65 2.9

Cavansite 1.539 1.542 1.544 1.544 1.546 1.551 0.009 0.009 2.21 2.31

Celestine 1.619 1.625 1.622 1.624 1.630 1.635 0.009 0.012 3.97 4

Celluloid 1.495 1.520 1.25 1.8

Cerussite 1.803 1.803 2.076 2.076 2.079 2.079 0.273 0.274 6.46 6.58

Ceylonite - spinel group 1.770 1.780 3.63 3.9

Chabazite 1.478 1.487 1.480 1.493 0.002 0.006 2.05 2.2

Chalcedony - crypto-cristalline quartz 1.538 1.548 1.530 1.540 0.008 0.010 2.58 2.91

Chambersite 1.732 1.732 1.737 1.737 1.744 1.744 0.012 0.012 3.49 3.51

Charlesite 1.462 1.475 1.480 1.498 0.010 0.036 1.7 1.84

Charoite 1.550 1.552 1.553 1.553 1.554 1.561 0.004 0.009 2.54 2.78

Childrenite 1.630 1.649 1.650 1.683 1.660 1.691 0.030 0.042 3.18 3.25

Chkalovite 1.540 1.544 1.544 1.546 1.549 1.550 0.003 0.009 2.65 2.67

Chlorastrolite -Pumpellyite- 1.674 1.702 1.675 1.715 1.688 1.722 0.014 0.022 3.1 3.5

Chondrodite - humite group- 1.589 1.643 1.602 1.655 1.618 1.670 0.025 0.036 3.1 3.35

Chrome diopside -diopside group 1.668 1.678 1.680 1.680 1.698 1.705 0.027 0.028 3.17 3.32

Chrysoberyl 1.739 1.759 1.742 1.764 1.748 1.770 0.007 0.012 3.68 3.8

Chrysoberyl - Alexandrite 1.739 1.759 1.742 1.764 1.748 1.770 0.007 0.011 3.68 3.8

Chrysoberyl - synthetic alexandrite 1.740 1.747 1.744 1.750 1.747 1.756 0.007 0.010 3.67 3.74

Chrysocolla 1.49

1.57 0.01 0.011 2.27 2.75

Cinnabar 3.256 3.256 2.905 2.905 0.351 0.351 8.09 8.1

Clinochlore 1.571 1.588 1.576 1.599 0.005 0.011 2.55 2.75

clinochlore - Kämmererite 1.585 1.597 1.587 1.600 0.002 0.003 2.64 2.67

Clinohumite - humite group 1.620 1.638 1.636 1.643 1.662 1.674 0.028 0.041 3.17 3.35

Clinozoisite - epidote group 1.670 1.715 1.675 1.725 1.690 1.734 0.005 0.019 3.2 3.4

Coeruleite -Ceruleite- 1.600 1.600 1.600 1.600 2.68 2.8

Colemanite 1.586 1.586 1.592 1.592 1.614 1.614 0.028 0.028 2.4 2.42

Copal 1.539 1.545 1 1.1

Coral 1.486 1.486 1.690 1.690 0.160 0.172 2.6 2.7

Coral imitation - Gilson 1.550 1.650 2.44 2.46

Cordierite - iolite 1.522 1.558 1.524 1.574 1.527 1.578 0.005 0.020 2.53 2.78

Corundum - Ruby 1.757 1.770 1.765 1.779 0.008 0.009 3.97 4.1

Corundum - Sapphire 1.757 1.770 1.765 1.779 0.008 0.009 3.97 4.1

Covellite 2.620 2.620 1.450 1.450 1.170 1.170 4.6 4.76

Creedite 1.460 1.460 1.478 1.478 1.485 1.485 0.024 0.025 2.71 2.73

Crocoite 2.290 2.310 2.370 2.370 2.660 2.660 0.350 0.350 5.9 6.1

Cr-Tourmaline - Tourmaline group 1.772 1.772 1.778 1.778 0.006 0.006 3.39 3.41

Cryolite 1.338 1.339 1.338 1.339 1.339 1.340 0.001 0.001 2.95 2.97

Cubic zirconia -CZ-, artificial product -Zirconia, fianite, djevalite- 2.008 2.182 5.55 6.16

cultured pearl 1.530 1.530 1.690 1.690 0.160 0.160 2.72 2.78

Cuprite 2.848 2.848 5.85 6.14

Danburite 1.628 1.633 1.630 1.637 1.633 1.641 0.004 0.008 2.97 3.03

Datolite 1.622 1.631 1.649 1.658 1.666 1.675 0.040 0.050 2.8 3

Demantoid - andradite -garnet group 1.880 1.889 3.8 3.88

Diamond 2.417 2.417 3.5 3.54

Diaspore 1.700 1.702 1.722 1.725 1.749 1.750 0.048 0.049 3.2 3.5

Diopside 1.664 1.695 1.672 1.701 1.695 1.721 0.024 0.031 3.22 3.38

Dioptase 1.697 1.709 1.644 1.658 0.051 0.053 3.28 3.35

Djevalite artificial product - Cubic Zirconia 2.172 2.182 5.6 5.7

Dolomite 1.500 1.520 1.679 1.703 0.179 0.185 2.8 2.95

Dravite - Tourmaline group 1.604 1.643 1.627 1.675 0.016 0.032 2.9 3.29

Dumortierite 1.659 1.686 1.682 1.722 1.685 1.723 0.018 0.037 3.2 3.48

dunilite - olivine group 1.663 1.680 1.686 1.700 1.700 1.719 0.040 0.041 3.46 3.55

Ekanite - metamict 1.590 1.596 1.591 1.597 0.001 0.001 3.26 3.32

Ekanite - not metamict 1.568 1.568 1.580 1.580 0.012 0.012 3.28 3.32

Elbaite - Tourmaline group 1.603 1.634 1.619 1.655 0.013 0.025 2.84 3.17

Elbaite Cu-bearing - Paraiba- Tourmaline group 1.618 1.621 1.638 1.642 0.018 0.021 3.04 3.13

Enstatite - enstatite group 1.650 1.666 1.653 1.671 1.658 1.684 0.009 0.015 3.2 3.33

Eosphorite 1.628 1.645 1.648 1.673 1.657 1.680 0.028 0.035 3.05 3.08

Epidote 1.712 1.751 1.725 1.784 1.734 1.797 0.015 0.049 3.3 3.5

Epistilbite 1.485 1.505 1.497 1.515 1.497 1.519 0.010 0.014 2.22 2.28

Ettringite 1.491 1.491 1.470 1.470 0.021 0.021 1.76 1.78

Euclase 1.650 1.654 1.655 1.658 1.671 1.677 0.019 0.025 2.99 3.13

Eucolite -Ca-rich eudialyte- 1.634 1.634 1.643 1.643 0.090 0.090 2.74 2.99

Eucryptite 1.583 1.587 1.570 1.573 0.013 0.015 2.65 2.67

Eudialyte 1.572 1.633 1.567 1.623 0.002 0.010 2.74 3.1

Euxenite 2.060 2.240 5.3 5.87

Fayalite - olivine group 1.827 1.827 1.869 1.869 1.879 1.879 0.052 0.052 4.39 4.39

Fergusonite 2.050 2.190 5.6 5.8

Ferroaxinite -axinite group 1.668 1.675 1.679 1.681 1.682 1.685 0.010 0.012 3.2 3.32

Fire opal 1.440 1.446 2 2.15

Fluorite 1.429 1.448 3 3.25

Forsterite - olivine group 1.635 1.730 1.651 1.739 1.669 1.772 0.032 0.042 3.2 3.51

Forsterite synthetic 1.635 1.640 1.641 1.654 1.670 1.671 0.032 0.035 3.21 3.26

Fresnoite 1.765 1.765 1.773 1.775 0.008 0.010 4.45 4.6

Friedelite 1.620 1.629 1.654 1.664 0.029 0.035 3.04 3.19

Gadolinite 1.770 1.780 1.780 1.820 0.010 0.040 4 4.65

Gahnite - spinel group 1.790 1.820 4.38 4.62

Gahnospinel - spinel group 1.723 1.753 3.58 4.06

Gaspeite 1.610 1.610 1.830 1.830 0.220 0.220 3.21 3.72

Gaylussiet 1.440 1.443 1.514 1.517 1.520 1.523 0.080 0.080 1.99 2.01

Genthelvite 1.738 1.752 3.44 3.7

GGG, artificial product 1.920 2.030 7.02 7.14

Glass 1.460 1.499 2.1 2.6

Glass 1.500 1.599 2.3 3.5

Glass 1.520 1.620 2.5 2.9

Glass 1.600 1.699 3.3 4.4

Glass 1.700 1.810 4.2 5.3

Glass 1.810 2.000 5.1 6.2

Görgeyite 1.556 1.560 1.569 1.570 1.584 1.587 0.024 0.027 2.9 2.93

Grandidierite 1.583 1.602 1.620 1.636 1.622 1.639 0.033 0.039 2.85 3

Greenockite 2.529 2.529 2.506 2.506 0.023 0.023 4.7 4.9

Grossular - garnet group 1.728 1.760 3.57 3.73

Gypsum - Alabaster 1.520 1.520 1.523 1.523 1.530 1.530 0.010 0.010 2.3 2.33

Hackmanite - sodalite 1.480 1.487 2.24 2.35

Hambergite 1.551 1.560 1.591 1.591 1.625 1.631 0.068 0.080 2.35 2.37

Haüyne 1.490 1.508 2.4 2.5

Hematite 2.870 2.940 3.150 3.220 0.280 0.280 4.95 5.28

Hemimorphite 1.614 1.614 1.617 1.617 1.636 1.636 0.022 0.022 3.3 3.5

Herderite 1.580 1.604 1.601 1.613 1.609 1.627 0.023 0.032 2.9 3.04

Hessonite - Grossular -Garnet group 1.738 1.763 3.47 3.73

Howlite 1.583 1.586 1.596 1.598 1.605 1.605 0.019 0.019 2.58 2.58

Hübnerite 2.170 2.200 2.220 2.220 2.300 2.320 0.130 0.130 7.12 7.18

Humite - humite group 1.607 1.643 1.639 1.675 0.029 0.031 3.2 3.32

Hyalophane 1.541 1.543 1.546 1.549 1.549 1.551 0.008 0.008 2.89 2.89

Hydrogrossular - Garnet group 1.632 1.744 2.76 3.69

Hydroxylherderite 1.610 1.612 1.630 1.631 1.641 1.642 0.030 0.031 2.95 2.95

Hypersthene - enstatite group 1.673 1.755 1.674 1.763 1.683 1.772 0.010 0.017 3.43 3.9

Inderite 1.486 1.489 1.488 1.493 1.504 1.507 0.017 0.020 1.78 1.86

Ivory 1.520 1.570 1.7 1.97

Ivory hornbill 1.520 1.550 1.28 1.29

Jadeite - jade group 1.640 1.658 1.645 1.663 1.652 1.667 0.012 0.020 3.25 3.36

Jeremejevite 1.637 1.644 1.644 1.653 0.007 0.013 3.27 3.33

Jet 1.640 1.660 1.19 1.35

Johachidolite 1.712 1.718 1.717 1.720 1.724 1.729 0.006 0.014 3.23 3.67

Kaliborite 1.503 1.508 1.526 1.527 1.549 1.550 0.041 0.043 2.11 2.13

Kornerupine 1.659 1.682 1.673 1.696 1.670 1.699 0.010 0.017 3.27 3.45

Kurnakovite 1.488 1.491 1.508 1.511 1.515 1.525 0.027 0.036 1.78 1.86

Kyanite 1.710 1.718 1.721 1.723 1.727 1.735 0.014 0.017 3.55 3.73

Kyanite-Cr 1.714 1.720 1.724 1.730 1.731 1.753 0.015 0.033 3.67 3.7

Labradorite - Plagioclase feldspar group 1.553 1.563 1.563 1.563 1.562 1.573 0.007 0.012 2.69 2.72

Langasite artificial product 1.909 1.909 1.921 1.921 1.921 1.921 1.910 1.910 0.011 0.011 4.65 4.65

Lapis Lazuli 1.500 1.500 2.5 3

Lawsonite 1.664 1.665 1.674 1.675 1.684 1.687 0.019 0.023 3.05 3.3

Lazulite 1.604 1.626 1.626 1.654 1.637 1.663 0.030 0.037 3.06 3.24

Lazurite 1.498 1.505 2.38 2.45

Legrandite 1.675 1.702 1.690 1.709 1.735 1.740 0.038 0.060 3.98 4.04

Leifite 1.519 1.522 1.511 1.518 0.004 0.010 2.57 2.63

Leucite 1.509 1.510 1.508 1.508 0.001 0.002 2.45 2.5

Leucophanite 1.565 1.565 1.590 1.590 1.593 1.593 0.028 0.028 2.97 3.06

Liddicoatite - Tourmaline group 1.619 1.621 1.637 1.651 0.014 0.027 3.02 3.11

Lithium fluoride, artificial 1.392 1.392 2.64 2.64

Lithium niobate, artificial product -linobate- 2.160 2.202 2.195 2.280 0.072 0.107 4.64 4.66

Lithium tantalate artificial product 2.180 2.180 2.175 2.175 0.005 0.005 7.3 7.5

Lizardite -serpentine group 1.538 1.554 1.546 1.568 0.005 0.022 2.51 2.6

Londonite 1.693 1.693 3.34 3.34

Ludlamite 1.650 1.653 1.669 1.675 1.688 1.697 0.038 0.044 3.12 3.19

Magnesioaxinite -axinite group 1.656 1.660 1.660 1.660 1.668 1.668 0.009 0.012 3.08 3.3

Magnesite 1.509 1.515 1.700 1.717 0.182 0.192 2.97 3.12

Magnetite 2.420 2.420 4.64 5.2

Malachite 1.655 1.655 1.875 1.875 1.909 1.909 0.254 0.254 3.75 3.95

Malaya garnet - Pyrope-Spessartine - Garnet group 1.750 1.780 3.82 4.05

Manganotantalite 2.140 2.190 2.220 2.340 0.080 0.150 7.73 8.1

Marcasite 4.8 4.9

Marialite - scapolite group 1.531 1.541 1.546 1.550 0.004 0.009 2.5 2.62

Maw-sit-sit -jade-albite- 1.520 1.540 2.46 3.15

Meionite -scapolite group 1.556 1.562 1.590 1.600 0.024 0.040 2.66 2.78

Mellite 1.509 1.511 1.539 1.541 0.028 0.032 1.55 1.65

Microcline -feldspar group 1.514 1.529 1.522 1.524 1.521 1.539 0.007 0.010 2.54 2.63

Microlite - pyrochlore group 1.930 2.020 4.3 6.4

Milarite 1.529 1.548 1.532 1.551 0.003 0.003 2.46 2.61

Mimetite 2.120 2.120 2.147 2.147 0.018 0.024 7.1 7.24

Moissanite synthetic 2.691 2.691 2.620 2.648 0.043 0.043 3.2 3.25

Monazite 1.774 1.800 1.777 1.801 1.828 1.849 0.049 0.055 4.8 5.5

Montebrasite -amblygonite group 1.594 1.615 1.608 1.624 1.616 1.646 0.020 0.050 2.98 3.05

Moonstone - Feldspar 1.518 1.520 1.522 1.524 1.524 1.527 0.006 0.007 2.56 2.6

Mordenite 1.472 1.483 1.475 1.485 1.477 1.487 0.005 0.005 2.12 2.15

Mosandrite 1.646 1.646 1.649 1.649 1.658 1.658 0.012 0.012 3.29 3.29

mother-of-pearl 1.530 1.530 1.690 1.690 0.160 0.160 2.61 2.78

Musgravite -magnesiotaaffeite-6N3S 1.715 1.720 1.719 1.728 0.004 0.007 3.61 3.69

Nambulite 1.707 1.707 1.710 1.710 1.730 1.730 0.023 0.023 3.51 3.51

Narsarsukite 1.632 1.655 1.601 1.614 0.031 0.041 2.64 2.83

Natrolite 1.473 1.485 1.476 1.486 1.485 1.496 0.005 0.014 2.2 2.26

Nepheline 1.526 1.544 1.529 1.549 0.003 0.005 2.55 2.66

Nephrite - jade group 1.600 1.627 1.614 1.641 0.027 0.030 2.9 3.03

Neptunite 1.690 1.691 1.693 1.700 1.719 1.736 0.029 0.045 3.19 3.23

Nifontovite 1.573 1.575 1.577 1.578 1.583 1.585 0.008 0.011 2.35 2.37

Nuumite 1.635 1.641 1.657 1.663 0.022 0.022 3.18 3.37

Obsidian 1.480 1.540 2.33 2.42

Oligoclase - plagioclase feldspar group 1.531 1.542 1.541 1.546 1.545 1.550 0.007 0.011 2.62 2.69

olmiite 1.663 1.663 1.672 1.672 1.694 1.694 0.031 0.031 3.05 3.1

Omphacite 1.662 1.701 1.670 1.712 1.685 1.723 0.023 0.023 3.29 3.39

Opal 1.370 1.475 1.95 2.25

Orthoclase - feldspar group 1.518 1.529 1.522 1.539 0.005 0.012 2.55 2.63

Painite 1.787 1.787 1.815 1.816 0.028 0.029 4 4.03

Pargasite 1.613 1.630 1.618 1.635 1.635 1.650 0.015 0.022 3.07 3.18

Parisite 1.757 1.772 1.671 1.676 0.075 0.101 4.33 4.38

Pectolite -larimar- 1.592 1.610 1.605 1.615 1.630 1.645 0.032 0.038 2.74 2.91

Periclase 1.735 1.745 3.55 3.68

Peridot - olivine group 1.640 1.655 1.657 1.673 1.675 1.690 0.033 0.040 3.27 3.43

Petalite 1.502 1.510 1.510 1.521 1.515 1.523 0.011 0.017 2.3 2.5

Pezzottaite 1.594 1.611 1.605 1.620 0.007 0.011 2.9 3.14

Phenakite 1.664 1.670 1.648 1.655 0.016 0.019 2.93 3

Phosgenite 2.140 2.145 2.114 2.118 0.028 0.028 6 6.3

Phosphophyllite 1.595 1.599 1.614 1.616 1.616 1.621 0.021 0.033 3.08 3.13

Plastics artificial product 1.490 1.700 1.3 1.95

Pleonast - spinel group 1.780 1.789 3.82 4.2

Poldervaartite 1.634 1.670 1.656 1.690 0.020 0.022 2.91 3.12

Pollucite 1.518 1.525 2.85 2.94

Polystyrene - artificial product 1.550 1.600 1.05 1.23

Porcelain - artificial product 1.550 1.660 2.3 2.5

Poudretteite 1.532 1.535 1.510 1.516 0.016 0.022 2.5 2.53

Powellite 1.978 1.985 1.967 1.974 0.011 0.011 4.17 4.28

Prehnite 1.611 1.632 1.615 1.642 1.632 1.665 0.021 0.033 2.8 2.95

Proustite 2.792 2.792 3.088 3.088 0.295 0.296 5.51 5.64

Psilomelane 2.110 2.110 2.260 2.260 0.150 0.150 4.4 4.7

Purpurite 1.850 1.850 1.860 1.860 1.920 1.920 0.070 0.070 3.37 3.37

Pyrargyrite 2.880 2.880 3.080 3.080 0.200 0.200 5.82 5.85

Pyrite 5 5.2

PYROPE -garnet group- 1.714 1.750 3.65 3.8

PYROPE-ALMANDINE -garnet group 1.742 1.785 3.75 3.95

PYROPE-SPESSARTINE -garnet group 1.750 1.780 3.8 4.11

Pyrophyllite -Agalmatolite- 1.534 1.556 1.586 1.589 1.596 1.601 0.050 0.050 2.65 2.9

Pyroxmangite 1.726 1.748 1.728 1.750 1.744 1.764 0.016 0.020 3.61 3.8

Quartz 1.553 1.553 1.544 1.544 0.009 0.009 2.64 2.66

Quartz synthetic hydrothermal 1.553 1.553 1.544 1.544 0.009 0.009 2.64 2.66

Quartzite 1.553 1.553 1.544 1.544 0.009 0.009 2.58 2.69

Realgar 2.538 2.538 2.684 2.684 2.704 2.704 0.166 0.166 3.56 3.56

Remondite 1.615 1.632 1.619 1.633 1.622 1.638 0.006 0.007 3.43 3.53

Rhodizite 1.689 1.694 3.28 3.54

Rhodochrosite 1.576 1.695 1.786 1.840 0.201 0.220 3.4 3.72

rhodolite - Pyrope-almandine - garnet group 1.750 1.765 3.8 3.89

Rhodonite 1.711 1.738 1.716 1.741 1.723 1.752 0.012 0.016 3.57 3.76

Richterite 1.605 1.624 1.618 1.640 1.627 1.641 0.017 0.022 2.97 3.45

Roselite 1.694 1.725 1.704 1.730 1.719 1.735 0.010 0.025 3.46 3.74

Rutile 2.900 2.900 2.620 2.620 0.287 0.287 4.2 5.6

Sanidine - feldspar group 1.516 1.527 1.522 1.524 1.522 1.534 0.004 0.008 2.56 2.6

Sapphirine 1.701 1.726 1.703 1.728 1.705 1.734 0.004 0.008 3.4 3.58

Scapolite 1.531 1.562 1.546 1.600 0.004 0.037 2.59 2.78

Scheelite 1.930 1.937 1.918 1.922 0.012 0.016 5.9 6.3

Schefferite - diopside group 1.676 1.676 1.683 1.683 1.705 1.705 0.031 0.031 3.39 3.39

Schorl - Tourmaline group 1.620 1.675 1.638 1.698 0.016 0.046 2.82 3.24

Scolecite 1.507 1.513 1.516 1.520 1.517 1.523 0.007 0.010 2.21 2.29

Scorodite 1.738 1.784 1.742 1.805 1.768 1.820 0.027 0.031 3.27 3.31

Scorzalite 1.627 1.639 1.655 1.670 1.664 1.680 0.038 0.041 3.27 3.38

Sekaninaite 1.559 1.561 1.572 1.572 1.573 1.576 0.015 0.017 2.76 2.77

Sellaite 1.389 1.390 1.378 1.379 0.010 0.012 3.14 3.16

Senarmontite 2.087 2.087 5.5 5.5

Sepiolite 1.518 1.520 1.525 1.530 0.010 0.010 1.98 2.02

Serandite 1.660 1.680 1.671 1.682 1.705 1.711 0.025 0.036 3 3.52

Serendibite 1.696 1.738 1.699 1.741 1.701 1.743 0.005 0.008 3.39 3.52

Shattuckite 1.752 1.753 1.782 1.782 1.815 1.815 0.063 0.063 3.8 4.11

Shortite 1.530 1.531 1.551 1.555 1.569 1.570 0.039 0.039 2.6 2.63

Siderite 1.592 1.633 1.816 1.875 0.240 0.242 3.78 3.96

Silicified wood - crypto-cristalline quartz 1.538 1.548 1.530 1.540 0.008 0.010 2.58 2.91

Sillimanite 1.654 1.661 1.658 1.662 1.673 1.684 0.014 0.021 3.22 3.27

Simpsonite 1.976 1.994 2.034 2.040 0.046 0.058 5.92 6.84

Sinhalite 1.665 1.678 1.697 1.697 1.704 1.712 0.035 0.042 3.47 3.5

Smithsonite 1.619 1.623 1.842 1.850 0.227 0.228 4.1 4.65

Sodalite 1.477 1.487 2.14 2.4

Sogdianite 1.606 1.606 1.608 1.608 0.002 0.002 2.76 2.9

Spessartine - garnet group 1.780 1.811 4.12 4.26

Sphalerite - Zinc blende 2.370 2.430 3.9 4.1

Spinel 1.711 1.722 3.55 3.63

Spodumene 1.653 1.670 1.660 1.669 1.665 1.682 0.014 0.027 3 3.24

Spurrite 1.637 1.641 1.672 1.674 1.676 1.682 0.039 0.040 3 3.02

Staurolite 1.732 1.759 1.742 1.764 1.744 1.761 0.011 0.015 3.65 3.83

Steatite - talc, soapstone 1.539 1.550 1.589 1.594 1.589 1.600 0.050 0.050 2.2 2.83

Stibiotantalite 2.370 2.374 2.400 2.400 2.457 2.460 0.083 0.090 7.34 7.46

Stichtite 1.516 1.518 1.540 1.545 0.022 0.028 2.13 2.22

Stolzite 2.190 2.190 2.270 2.270 0.080 0.080 7.9 8.34

Strontium titanate -fabulite- artificial product 2.400 2.410 5.11 5.15

Sturmanite 1.505 1.505 1.499 1.500 0.005 0.006 1.84 1.86

Sugilite 1.590 1.607 1.595 1.611 0.003 0.005 2.69 2.79

Sulfur 1.958 1.958 2.245 2.245 0.291 0.291 2.05 2.09

Suolunite 1.610 1.612 1.620 1.620 1.623 1.623 0.011 0.013 2.63 2.68

Synthetic Cassiterite 2.093 2.093 1.997 1.997 0.096 0.096 6.8 7.1

Synthetic corundum 1.757 1.768 1.765 1.776 0.008 0.008 3.9 4.05

Synthetic diamond 2.417 2.417 3.52 3.52

Synthetic fresnoite 1.765 1.765 1.775 1.775 0.010 0.010 4.45 4.45

Synthetic Gahnite 1.805 1.805 4.4 4.4

synthetic Lapis Lazuli 1.500 1.550 2.3 2.4

Synthetic opal - China 1.450 1.468 1.8 1.9

Synthetic opal - Gilson 1.410 1.450 1.91 2.24

Synthetic opal - Inamori 1.463 1.466 2.23 2.24

Synthetic opal - Inamori 1.460 1.460 2.2 2.24

Synthetic opal - Russia 1.440 1.450 1.74 1.86

Synthetic Powellite 1.984 1.984 1.924 1.924 0.060 0.060 4.34 4.34

Synthetic rutile 2.710 2.710 2.450 2.450 0.260 0.260 4.23 4.45

Synthetic scheelite 1.936 1.936 1.920 1.920 0.016 0.016 5.9 6.11

Synthetic sodalite 1.480 1.480 2.42 2.42

Synthetic Sphalerite 2.250 2.350 4.03 4.09

Synthetic spinel - flux grown - spinel group 1.715 1.735 3.58 3.63

Synthetic spinel - Verneuil - spinel group 1.723 1.740 3.6 3.78

Synthetic spinel -sintered - spinel group 1.711 1.725 3.52 3.54

synthetic Turquoise 1.590 1.600 1.650 1.650 0.040 0.040 2.68 2.75

Synthetic zincite 2.029 2.030 2.010 2.013 0.016 0.016 5.4 5.7

Taaffeite 1.715 1.730 1.719 1.735 0.004 0.009 3.59 3.72

Tanzanite - zoisite - epidote group 1.690 1.690 1.693 1.693 1.702 1.702 0.006 0.012 3.33 3.36

Tektite - Australite 1.500 1.510 2.38 2.46

Tektite - Bediasite 1.480 1.500 2.33 2.43

Tektite - Billitonite 1.510 1.520 2.46 2.51

Tektite - Darwin glass 1.470 1.482 2.26 2.96

Tektite - Georgia tektite/ Massachussetts tektite 1.485 1.485 2.33 2.34

Tektite - Indochinite 1.490 1.500 2.4 2.44

Tektite - Ivory Coast tektite 1.500 1.510 2.4 2.52

Tektite - Javaite 1.509 1.510 2.43 2.45

Tektite - Libyan desert glass 1.460 1.465 2.2 2.22

Tektite - Moldavite 1.480 1.540 2.27 2.4

Tektite - Philippinite 1.510 1.510 2.44 2.45

Tephroite 1.770 1.788 1.807 1.810 1.817 1.825 0.037 0.047 4.11 4.11

Thaumasite 1.464 1.480 1.500 1.511 0.030 0.039 1.87 1.91

Thomsonite 1.511 1.530 1.513 1.532 1.516 1.545 0.005 0.021 2.23 2.4

Thortveitite 1.750 1.756 1.789 1.793 1.802 1.809 0.052 0.056 3.27 3.58

Thulite - zoisite - epidote group 1.695 1.695 1.701 1.701 0.006 0.006 3.09 3.09

Tiger's eye - crypto-cristalline quartz 1.538 1.548 1.530 1.540 0.008 0.010 2.58 2.91

Titanite 1.843 1.950 1.943 2.110 0.100 0.160 3.45 3.55

Topaz 1.605 1.635 1.609 1.637 1.616 1.649 0.008 0.011 3.52 3.58

Tortoise shell 1.530 1.586 1.26 1.35

Tremolite - hexagonite 1.599 1.613 1.613 1.626 1.625 1.637 0.023 0.028 2.9 3.03

Triphylite 1.689 1.694 1.689 1.695 1.695 1.702 0.006 0.008 3.34 3.58

Triplite 1.644 1.684 1.647 1.693 1.668 1.703 0.019 0.030 3.44 3.9

Triploidite 1.709 1.735 1.714 1.740 0.015 0.019 3.7 3.8

Triploidite2 1.660 1.660 1.679 1.679 0.019 0.019 3.8 3.83

Tsavorite - grossular - garnet group 1.732 1.743 3.55 3.73

Tsilaisite - Tourmaline group 1.621 1.623 1.645 1.649 0.023 0.028 3.12 3.14

Tugtupite 1.499 1.502 1.492 1.496 0.006 0.007 2.27 2.57

Turquoise 1.610 1.610 1.620 1.620 1.650 1.650 0.040 0.040 2.6 2.9

Turquoise dyed 1.610 1.610 1.620 1.620 1.650 1.650 0.040 0.040 2.14 2.36

Turquoise impregnated 1.610 1.610 1.620 1.620 1.650 1.650 0.040 0.040 2.15 2.35

Turquoise reconstructed 1.440 1.450 2.4 2.6

Turquoise stabilized 1.610 1.610 1.620 1.620 1.650 1.650 0.040 0.040 2.2 2.4

Ulexite 1.496 1.496 1.505 1.505 1.519 1.519 0.023 0.023 1.65 1.95

Unakite 1.520 1.760 2.85 3.2

Ussingite 1.504 1.504 1.508 1.508 1.543 1.543 0.039 0.039 2.46 2.5

Uvarovite - garnet group 1.870 1.870 3.71 3.77

Uvite - Tourmaline group 1.612 1.639 1.632 1.660 0.017 0.023 3.01 3.09

Vanadinite 2.350 2.350 2.416 2.416 0.066 0.066 6.5 7.24

Variscite 1.563 1.563 1.588 1.588 1.594 1.594 0.031 0.031 2.2 2.57

Väyrynenite 1.638 1.649 1.658 1.661 1.664 1.670 0.023 0.028 3.18 3.25

Verdite 1.578 1.582 2.86 2.89

Vesuvianite - Idocrase 1.674 1.761 1.655 1.750 0.001 0.018 3.32 3.47

Vienna turquoise 1.450 1.450 2.39 2.49

Villiaumite 1.326 1.332 2.78 2.81

Vlasovite 1.607 1.609 1.623 1.623 1.624 1.628 0.015 0.021 2.95 3

Wernerite - scapolite group 1.549 1.549 1.567 1.567 0.004 0.020 2.6 2.78

Whewellite 1.488 1.490 1.553 1.555 1.649 1.652 0.159 0.162 2.19 2.25

Willemite 1.715 1.730 1.690 1.720 0.010 0.033 3.89 4.19

Williamsite - serpentine group 1.532 1.532 1.556 1.556 0.013 0.024 2.53 2.65

Witherite 1.529 1.532 1.676 1.678 1.677 1.680 0.148 0.148 4.27 4.35

Wulfenite 2.283 2.283 2.405 2.405 0.122 0.122 6.5 7

Xenotime 1.816 1.827 1.719 1.724 0.096 0.103 4.3 5.1

Xonotlite 1.583 1.583 1.585 1.585 1.593 1.593 0.010 0.010 2.71 2.71

YAG, artificial product Yttrium-aluminium garnet 1.833 1.885 4.55 5.05

YGG, artificial product Yttrium-gallium garnet 1.970 1.970 5.75 5.75

YIG, artificial product Yttrium-iron garnet 1.938 1.955 5.33 5.36

Yttrium aluminate YALO, artificial product 1.938 1.938 1.955 1.955 0.017 0.017 5.33 5.36

Yttrium oxide - Yttralox artificial product 1.920 1.920 4.84 4.84

Yugawaralite 1.490 1.495 1.497 1.503 1.501 1.509 0.011 0.014 2.19 2.25

Zektzerite 1.582 1.582 1.584 1.584 1.584 1.584 0.002 0.002 2.79 2.79

Zincite 2.029 2.029 2.013 2.013 0.016 0.016 5.43 5.7

Zircon 1.781 2.015 1.777 1.960 0.000 0.055 3.9 4.73

Zircon - high 1.970 2.010 1.925 1.940 0.036 0.059 4.65 4.8

Zircon - low 1.781 1.850 1.777 1.850 0.000 0.004 3.9 4.1

Zircon - medium 1.850 1.970 1.846 1.930 0.006 0.043 4.08 4.65

Zn-Taaffeite 1.724 1.730 1.729 1.735 0.004 0.006 3.69 3.78

Zoisite - epidote group 1.685 1.705 1.688 1.710 1.697 1.725 0.004 0.012 3.15 3.55