Dispersion des Gemmes — Tableau de Référence du Feu
Valeurs de dispersion (intervalle B–G) pour 115 espèces de gemmes, classées de la plus forte à la plus faible. La dispersion est la propriété à l'origine du « feu » : les éclats de couleur que projette une pierre taillée lorsqu'elle bouge. La taille détermine la part de ce feu réellement visible, mais le plafond est fixé par cette constante.
Les noms des gemmes figurent sous leur forme commerciale internationale (anglais) et renvoient à la fiche détaillée de chaque espèce (en anglais).
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Essayer Loupewise Gratuitement →| Gemme | Dispersion (B–G) | Plage IR | Caractère Optique | Dureté |
|---|---|---|---|---|
| Cinnabar | 0.400 | 2.905–3.256 | Uniaxial (+) | 2–2.5 |
| Sphalerite | 0.156 | 2.369–2.371 | SR | 3.5–4 |
| Cuprite | 0.155 | 2.849 | SR | 3.5–4 |
| Moissanite | 0.104 | 2.648–2.691 | Uniaxial (+) | 9.25 |
| Cassiterite | 0.071 | 1.997–2.093 | Uniaxial (+) | 6–7 |
| Cubic Zirconia | 0.066 | 2.150–2.180 | SR | 8–8.5 |
| Demantoid Garnet | 0.057 | 1.880–1.895 | SR | 6.5–7 |
| Sphene | 0.051 | 1.843–2.110 | Biaxial (+) | 5–5.5 |
| Benitoite | 0.046 | 1.757–1.804 | Uniaxial (+) | 6–6.5 |
| Blue Diamond | 0.044 | 2.417 | SR | 10 |
| Brown Diamond | 0.044 | 2.417 | SR | 10 |
| Diamond | 0.044 | 2.417 | SR | 10 |
| Pink Diamond | 0.044 | 2.417 | SR | 10 |
| Yellow Diamond | 0.044 | 2.417 | SR | 10 |
| Zircon | 0.039 | 1.925–1.984 | Uniaxial (+) | 7.5 |
| Low-Type Zircon | 0.038 | 1.780–1.815 | SR | 6 |
| Tanzanite | 0.030 | 1.691–1.700 | Biaxial (+) | 6–7 |
| Grossular Garnet | 0.028 | 1.734–1.759 | SR | 6.5–7.5 |
| Hessonite Garnet | 0.028 | 1.730–1.760 | SR | 7–7.5 |
| Tsavorite Garnet | 0.028 | 1.730–1.760 | SR | 7–7.5 |
| YAG | 0.028 | 1.833 | SR | 8–8.5 |
| Spessartite Garnet | 0.027 | 1.790–1.815 | SR | 7–7.5 |
| Color-Change Garnet | 0.026 | 1.740–1.765 | SR | 7–7.5 |
| Rhodolite Garnet | 0.026 | 1.740–1.770 | SR | 7–7.5 |
| Malachite | 0.025 | 1.655–1.909 | Biaxial (−) | 3.5–4 |
| Almandine Garnet | 0.024 | 1.770–1.830 | SR | 7–7.5 |
| Star Garnet | 0.024 | 1.770–1.830 | SR | 7–7.5 |
| Malaya / Umbalite Garnet | 0.023 | 1.730–1.780 | SR | 7–7.5 |
| Clinohumite | 0.022 | 1.625–1.675 | Biaxial (+) | 6 |
| Pyrope Garnet | 0.022 | 1.730–1.760 | SR | 7–7.5 |
| Black Spinel | 0.020 | 1.712–1.730 | SR | 8 |
| Chrome Diopside | 0.020 | 1.664–1.730 | Biaxial (+) | 5.5–6.5 |
| Diaspore | 0.020 | 1.702–1.752 | Biaxial (+) | 6.5–7 |
| Kyanite | 0.020 | 1.712–1.734 | Biaxial (−) | 4.5–7 |
| Opal | 0.020 | 1.370–1.470 | SR | 5.5–6.5 |
| Peridot | 0.020 | 1.654–1.690 | Biaxial (+) | 6.5–7 |
| Prehnite | 0.020 | 1.611–1.665 | Biaxial (+) | 6–6.5 |
| Spinel | 0.020 | 1.712–1.736 | SR | 7.5–8 |
| Synthetic Spinel | 0.020 | 1.725–1.728 | SR | 8 |
| Hauyne | 0.019 | 1.494–1.509 | SR | 5.5–6 |
| Taaffeite | 0.019 | 1.719–1.723 | Uniaxial (−) | 8–8.5 |
| Color-Change Sapphire | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Hackmanite | 0.018 | 1.483–1.487 | SR | 5.5–6 |
| Kornerupine | 0.018 | 1.660–1.699 | Biaxial (−) | 6.5 |
| Padparadscha Sapphire | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Pink Sapphire | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Ruby | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Sapphire | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Sinhalite | 0.018 | 1.665–1.712 | Biaxial (−) | 6.5–7 |
| Star Ruby | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Star Sapphire | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Synthetic Color-Change Corundum | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| White Sapphire | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Yellow Sapphire | 0.018 | 1.762–1.770 | Uniaxial (−) | 9 |
| Calcite | 0.017 | 1.486–1.658 | Uniaxial (−) | 3 |
| Chrome Tourmaline | 0.017 | 1.624–1.660 | Uniaxial (−) | 7–7.5 |
| Danburite | 0.017 | 1.627–1.636 | Biaxial (−) | 7–7.5 |
| Enstatite | 0.017 | 1.663–1.673 | Biaxial (+) | 5–5.5 |
| Green Tourmaline | 0.017 | 1.616–1.650 | Uniaxial (−) | 7–7.5 |
| Hiddenite | 0.017 | 1.660–1.676 | Biaxial (+) | 6.5–7 |
| Indicolite | 0.017 | 1.624–1.644 | Uniaxial (−) | 7–7.5 |
| Iolite | 0.017 | 1.540–1.560 | Biaxial (−) | 7–7.5 |
| Kunzite | 0.017 | 1.660–1.676 | Biaxial (+) | 6.5–7 |
| Paraiba Tourmaline | 0.017 | 1.624–1.644 | Uniaxial (−) | 7–7.5 |
| Rubellite | 0.017 | 1.624–1.644 | Uniaxial (−) | 7–7.5 |
| Scapolite | 0.017 | 1.540–1.572 | Uniaxial (−) | 6–6.5 |
| Tourmaline | 0.017 | 1.624–1.644 | Uniaxial (−) | 7–7.5 |
| Watermelon Tourmaline | 0.017 | 1.616–1.650 | Uniaxial (−) | 7–7.5 |
| Andalusite | 0.016 | 1.629–1.649 | Biaxial (−) | 7–7.5 |
| Rhodonite | 0.016 | 1.716–1.752 | Biaxial (+) | 5.5–6.5 |
| Variscite | 0.016 | 1.560–1.594 | Biaxial (−) | 3.5–4.5 |
| Alexandrite | 0.015 | 1.746–1.755 | Biaxial (+) | 8.5 |
| Cat's Eye Chrysoberyl | 0.015 | 1.746–1.755 | Biaxial (+) | 8.5 |
| Chrysoberyl | 0.015 | 1.746–1.755 | Biaxial (+) | 8.5 |
| Grandidierite | 0.015 | 1.590–1.623 | Biaxial (−) | 7–7.5 |
| Phenakite | 0.015 | 1.654–1.670 | Uniaxial (+) | 7.5–8 |
| Rhodochrosite | 0.015 | 1.600–1.820 | Uniaxial (−) | 3.5–4 |
| Aquamarine | 0.014 | 1.577–1.583 | Uniaxial (−) | 7.5–8 |
| Emerald | 0.014 | 1.565–1.602 | Uniaxial (−) | 7.5–8 |
| Goshenite | 0.014 | 1.577–1.583 | Uniaxial (−) | 7.5–8 |
| Heliodor | 0.014 | 1.568–1.580 | Uniaxial (−) | 7.5–8 |
| Morganite | 0.014 | 1.572–1.600 | Uniaxial (−) | 7.5–8 |
| Red Beryl | 0.014 | 1.564–1.574 | Uniaxial (−) | 7.5–8 |
| Topaz | 0.014 | 1.609–1.643 | Biaxial (+) | 8 |
| Agate | 0.013 | 1.530–1.543 | Agrégat | 6.5–7 |
| Amethyst | 0.013 | 1.544–1.553 | Uniaxial (+) | 7 |
| Ametrine | 0.013 | 1.544–1.553 | Uniaxial (+) | 7 |
| Apatite | 0.013 | 1.628–1.649 | Uniaxial (−) | 5 |
| Aventurine | 0.013 | 1.544–1.553 | Agrégat | 7 |
| Bloodstone | 0.013 | 1.530–1.543 | Agrégat | 6.5–7 |
| Carnelian | 0.013 | 1.530–1.543 | Agrégat | 6.5–7 |
| Chalcedony | 0.013 | 1.530–1.543 | Agrégat | 6.5–7 |
| Chrysoprase | 0.013 | 1.530–1.543 | Agrégat | 6.5–7 |
| Citrine | 0.013 | 1.544–1.553 | Uniaxial (+) | 7 |
| Hawk's Eye | 0.013 | 1.544–1.553 | Agrégat | 7 |
| Onyx | 0.013 | 1.530–1.543 | Agrégat | 6.5–7 |
| Prasiolite | 0.013 | 1.544–1.553 | Uniaxial (+) | 7 |
| Rock Crystal | 0.013 | 1.544–1.553 | Uniaxial (+) | 7 |
| Rose Quartz | 0.013 | 1.544–1.553 | Uniaxial (+) | 7 |
| Smoky Quartz | 0.013 | 1.544–1.553 | Uniaxial (+) | 7 |
| Star Diopside | 0.013 | 1.664–1.721 | Biaxial (+) | 5–6 |
| Tiger's Eye | 0.013 | 1.544–1.553 | Agrégat | 7 |
| Chrysocolla Chalcedony | 0.013 | 1.530–1.543 | Agrégat | 6.5–7 |
| Amazonite | 0.012 | 1.514–1.530 | Biaxial (−) | 6–6.5 |
| Labradorite | 0.012 | 1.559–1.573 | Biaxial (+) | 6–6.5 |
| Moonstone | 0.012 | 1.518–1.526 | Biaxial (−) | 6–6.5 |
| Rainbow Moonstone | 0.012 | 1.559–1.572 | Biaxial (−) | 6–6.5 |
| Sunstone | 0.012 | 1.537–1.572 | Biaxial (−) | 6–6.5 |
| Thulite | 0.012 | 1.691–1.704 | Biaxial (+) | 6–7 |
| Larimar | 0.010 | 1.595–1.640 | Biaxial (+) | 4.5–5 |
| Moldavite | 0.010 | 1.480–1.510 | SR | 5.5 |
| Obsidian | 0.010 | 1.480–1.510 | SR | 5–5.5 |
| Sugilite | 0.010 | 1.607–1.610 | Uniaxial (−) | 5.5–6.5 |
| Fluorite | 0.007 | 1.432–1.436 | SR | 4 |
| Charoite | 0.005 | 1.550–1.559 | Agrégat | 5–6 |
Quelle gemme a la dispersion la plus élevée ?
Parmi les 132 gemmes de cette référence, Cinnabar a la dispersion la plus élevée (0.400), devant Sphalerite (0.156), Cuprite (0.155), Moissanite (0.104). Le diamant mesure 0.044.
La moissanite a-t-elle plus de feu que le diamant ?
Oui : la dispersion de la moissanite est de 0.104 contre 0.044 pour le diamant, soit plus du double. Un feu excessif dans un prétendu diamant est le premier indice pratique, confirmé par le dédoublement des facettes (biréfringence 0.043).
Voir aussi: Reference Database (EN) · Guide (EN)