Editing Dispersion (optics) (section)

== In gemology ==
{| class="wikitable sortable collapsible collapsed" style="float: right; text-align: center;"
|+ Dispersion values of minerals<ref name="b1">{{cite book |last=Schumann |first=Walter |year=2009 |title=Gemstones of the World |edition=4th newly revised & expanded |publisher=Sterling Publishing Company |isbn=978-1-4027-6829-3 |pages=41–42 |url=https://books.google.com/books?id=V9PqVxpxeiEC&pg=PA42 |access-date=31 December 2011}}</ref>
! Mineral name !! {{nobr|{{mvar|n}}{{sub|{{sc|B}} }} − {{mvar|n}}{{sub|{{sc|G}} }} }} !! {{nobr|{{mvar|n}}{{sub|{{sc|C}} }} − {{mvar|n}}{{sub|{{sc|F}} }} }}
|-
| [[Hematite]] || 0.500 || —
|-
| [[Cinnabar]] (HgS) || 0.40 || —
|-
| synth. [[Rutile]] || 0.330 || 0.190
|-
| [[Rutile]] (TiO<sub>2</sub>) || 0.280 || 0.120–0.180
|-
| [[Anatase]] (TiO<sub>2</sub>) || 0.213–0.259 || —
|-
| [[Wulfenite]] || 0.203 || 0.133
|-
| [[Vanadinite]] || 0.202 || —
|-
| [[Fabulite]] || 0.190 || 0.109
|-
| [[Sphalerite]] (ZnS) || 0.156 || 0.088
|-
| [[Sulfur]] (S) || 0.155 || —
|-
| [[Stibiotantalite]] || 0.146 || —
|-
| [[Goethite]] (FeO(OH)) || 0.14 || —
|-
| [[Brookite]] (TiO<sub>2</sub>) || 0.131 || 0.12–1.80
|-
| [[Linobate]] || 0.13 || 0.075
|-
| [[Zincite]] (ZnO) || 0.127 || —
|-
| synth. [[Moissanite]] (SiC) || 0.104 || —
|-
| [[Cassiterite]] (SnO<sub>2</sub>) || 0.071 || 0.035
|-
| [[Zirconia]] (ZrO<sub>2</sub>) || 0.060 || 0.035
|-
| [[Powellite]] (CaMoO<sub>4</sub>) || 0.058 || —
|-
| [[Andradite]] || 0.057 || —
|-
| [[Demantoid]] || 0.057 || 0.034
|-
| [[Cerussite]] || 0.055 || 0.033–0.050
|-
| [[Titanite]] || 0.051 || 0.019–0.038
|-
| [[Benitoite]] || 0.046 || 0.026
|-
| [[Anglesite]] || 0.044 || 0.025
|-
| [[Diamond]] (C) || 0.044 || 0.025
|-
| synth. [[Cassiterite]] (SnO<sub>2</sub>) || 0.041 || —
|-
| [[Flint glass]] || 0.041 || —
|-
| [[Hyacinth (mineral)|Hyacinth]] || 0.039 || —
|-
| [[Jargoon]] || 0.039 || —
|-
| [[Starlite]] || 0.039 || —
|-
| [[Scheelite]] || 0.038 || 0.026
|-
| [[Zircon]] (ZrSiO<sub>4</sub>) || 0.039 || 0.022
|-
| [[Gadolinium gallium garnet|GGG]] || 0.038 || 0.022
|-
| [[Dioptase]] || 0.036 || 0.021
|-
| [[Whe Vinay wellite]] || 0.034 || —
|-
| [[Gypsum]] || 0.033 || 0.008
|-
| [[Alabaster]] || 0.033 || —
|-
| [[Epidote]] || 0.03 || 0.012–0.027
|-
| [[Tanzanite]] || 0.030 || 0.011
|-
| [[Thulite]] || 0.03 || 0.011
|-
| [[Zoisite]] || 0.03 || —
|-
| [[Yttrium aluminium garnet|YAG]] || 0.028 || 0.015
|-
| [[Spessartine]] || 0.027 || 0.015
|-
| [[Uvarovite]] || 0.027 || 0.014–0.021
|-
| [[Almandine]] || 0.027 || 0.013–0.016
|-
| [[Hessonite]] || 0.027 || 0.013–0.015
|-
| [[Willemite]] || 0.027 || —
|-
| [[Pleonaste]] || 0.026 || —
|-
| [[Rhodolite]] || 0.026 || —
|-
| [[Boracite]] || 0.024 || 0.012
|-
| [[Cryolite]] || 0.024 || —
|-
| [[Staurolite]] || 0.023 || 0.012–0.013
|-
| [[Pyrope]] || 0.022 || 0.013–0.016
|-
| [[Diaspore]] || 0.02 || —
|-
| [[Grossular]] || 0.020 || 0.012
|-
| [[Hemimorphite]] || 0.020 || 0.013
|-
| [[Kyanite]] || 0.020 || 0.011
|-
| [[Peridot]] || 0.020 || 0.012–0.013
|-
| [[Spinel]] || 0.020 || 0.011
|-
| [[Vesuvianite]] || 0.019–0.025 || 0.014
|-
| [[Gahnite]] || 0.019–0.021 || —
|-
| [[Clinozoisite]] || 0.019 || 0.011–0.014
|-
| [[Labradorite]] || 0.019 || 0.010
|-
| [[Axinite]] || 0.018–0.020 || 0.011
|-
| [[Diopside]] || 0.018–0.020 || 0.01
|-
| [[Ekanite]] || 0.018 || 0.012
|-
| [[Corundum]] (Al<sub>2</sub>O<sub>3</sub>) || 0.018 || 0.011
|-
| synth. [[Corundum]] || 0.018 || 0.011
|-
| [[Ruby]] (Al<sub>2</sub>O<sub>3</sub>) || 0.018 || 0.011
|-
| [[Sapphire]] (Al<sub>2</sub>O<sub>3</sub>) || 0.018 || 0.011
|-
| [[Kornerupine]] || 0.018 || 0.010
|-
| [[Sinhalite]] || 0.018 || 0.010
|-
| [[Sodalite]] || 0.018 || 0.009
|-
| [[Rhodizite]] || 0.018 || —
|-
| [[Hiddenite]] || 0.017 || 0.010
|-
| [[Kunzite]] || 0.017 || 0.010
|-
| [[Spodumene]] || 0.017 || 0.010
|-
| [[Tourmaline]] || 0.017 || 0.009–0.011
|-
| [[Cordierite]] || 0.017 || 0.009
|-
| [[Danburite]] || 0.017 || 0.009
|-
| [[Herderite]] || 0.017 || 0.008–0.009
|-
| [[Rubellite]] || 0.017 || 0.008–0.009
|-
| [[Achroite]] || 0.017 || —
|-
| [[Dravite]] || 0.017 || —
|-
| [[Elbaite]] || 0.017 || —
|-
| [[Indicolite]] || 0.017 || —
|-
| [[Liddicoatite]] || 0.017 || —
|-
| [[Scapolite]] || 0.017 || —
|-
| [[Schorl]] || 0.017 || —
|-
| [[Verdelite]] || 0.017 || —
|-
| [[Andalusite]] || 0.016 || 0.009
|-
| [[Baryte]] (BaSO<sub>4</sub>) || 0.016 || 0.009
|-
| [[Euclase]] || 0.016 || 0.009
|-
| [[Datolite]] || 0.016 || —
|-
| [[Alexandrite]] || 0.015 || 0.011
|-
| [[Chrysoberyl]] || 0.015 || 0.011
|-
| [[Rhodochrosite]] || 0.015 || 0.010–0.020
|-
| [[Sillimanite]] || 0.015 || 0.009–0.012
|-
| [[Hambergite]] ||  0.015 || 0.009–0.010
|-
| [[Pyroxmangite]] || 0.015 || —
|-
| synth. [[Scheelite]] || 0.015 || —
|-
| [[Smithsonite]] || 0.014–0.031 || 0.008–0.017
|-
| [[Amblygonite]] || 0.014–0.015 || 0.008
|-
| [[Aquamarine (gemstone)|Aquamarine]] || 0.014 || 0.009–0.013
|-
| [[Beryl]] || 0.014 || 0.009–0.013
|-
| [[Emerald]] || 0.014 || 0.009–0.013
|-
| [[Heliodor]] || 0.014 || 0.009–0.013
|-
| [[Morganite]] || 0.014 || 0.009–0.013
|-
| [[Brazilianite]] || 0.014 || 0.008
|-
| [[Celestine (mineral)|Celestine]] || 0.014 || 0.008
|-
| [[Topaz]] || 0.014 || 0.008
|-
| [[Goshenite]] || 0.014 || —
|-
| [[Apatite]] || 0.013 || 0.008–0.010
|-
| [[Aventurine]] || 0.013 || 0.008
|-
| [[Amethyst]] (SiO<sub>2</sub>) || 0.013 || 0.008
|-
| [[Citrine quartz]] || 0.013 || 0.008
|-
| [[Prasiolite]] || 0.013 || 0.008
|-
| [[Quartz]] (SiO<sub>2</sub>) || 0.013 || 0.008
|-
| Rose quartz (SiO<sub>2</sub>) || 0.013 || 0.008
|-
| Smoky quartz (SiO<sub>2</sub>) || 0.013 || 0.008
|-
| [[Anhydrite]] || 0.013 || —
|-
| [[Dolomite (mineral)|Dolomite]] || 0.013 || —
|-
| [[Morion (mineral)|Morion]] || 0.013 || —
|-
| [[Feldspar]] || 0.012 || 0.008
|-
| [[Moonstone (gemstone)|Moonstone]] || 0.012 || 0.008
|-
| [[Orthoclase]] || 0.012 || 0.008
|-
| [[Pollucite]] || 0.012 || 0.007
|-
| [[Albite]] || 0.012 || —
|-
| [[Bytownite]] || 0.012 || —
|-
| [[Emerald#Synthetic emerald|synth. Emerald]] || 0.012 || —
|-
| [[Magnesite]] (MgCO<sub>3</sub>) || 0.012 || —
|-
| [[Sanidine]] || 0.012 || —
|-
| [[Sunstone]] || 0.012 || —
|-
| synth. [[Alexandrite]] || 0.011 || —
|-
| synth. [[Sapphire]] (Al<sub>2</sub>O<sub>3</sub>) || 0.011 || —
|-
| [[Phosphophyllite]] || 0.010–0.011 || —
|-
| [[Phenakite]] || 0.01 || 0.009
|-
| [[Cancrinite]] || 0.010 || 0.008–0.009
|-
| [[Leucite]] || 0.010 || 0.008
|-
| [[Enstatite]] || 0.010 || —
|-
| [[Obsidian]] || 0.010 || —
|-
| [[Anorthite]] || 0.009–0.010 || —
|-
| [[Actinolite]] || 0.009 || —
|-
| [[Jeremejevite]] || 0.009 || —
|-
| [[Nepheline]] || 0.008–0.009 || —
|-
| [[Apophyllite]] || 0.008 || —
|-
| [[Hauyne]] || 0.008 || —
|-
| [[Natrolite]] || 0.008 || —
|-
| synth. [[Quartz]] (SiO<sub>2</sub>) || 0.008 || —
|-
| [[Aragonite]] || 0.007–0.012 || —
|-
| [[Augelite]] || 0.007 || —
|-
| [[Beryllonite]] || 0.010 || 0.007
|-
| [[Strontianite]] || 0.008–0.028 || —
|-
| [[Calcite]] (CaCO<sub>3</sub>) || 0.008–0.017 || 0.013–0.014
|-
| [[Fluorite]] (CaF<sub>2</sub>) || 0.007 || 0.004
|-
| [[Tremolite]] || 0.006–0.007 || —
|}

In the [[technical terminology]] of [[gemology]], ''dispersion'' is the difference in the refractive index of a material at the B and G (686.7&nbsp;[[Nanometre|nm]] and 430.8&nbsp;nm) or C and F (656.3&nbsp;nm and 486.1&nbsp;nm) [[Fraunhofer lines|Fraunhofer wavelengths]], and is meant to express the degree to which a prism cut from the [[gemstone]] demonstrates "fire".  Fire is a colloquial term used by gemologists to describe a gemstone's dispersive nature or lack thereof. Dispersion is a material property. The amount of fire demonstrated by a given gemstone is a function of the gemstone's facet angles, the polish quality, the lighting environment, the material's refractive index, the saturation of color, and the orientation of the viewer relative to the gemstone.<ref name="b1" /><ref>{{cite web |title=What is gemstone dispersion? |website=International Gem Society (GemSociety.org) |url=http://www.gemsociety.org/article/gemstone-dispersion/ |access-date=2015-03-09}}</ref>