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By Reviewed By Andreas Zabczyk

Refractive Index Chart of Gemstones - Find quickly all Values in a Table or List with Images

Click on any Letter below to see all assosiated gemstones with images and details.

Refractive index, or RI is one of the most important signatures of a gemstone. Measuring the refractive index is one of the first steps in identifying a gemstone, though some gems have similar refractive indices and additional tests are required for a definitive identification.

RI is the difference between the speed of light in a vacuum and the speed of light in the gemstone. As light passes through a gemstone, it slows down because a gemstone is denser than air. This causes the path of light to change. Refraction is the bending of light as it passes in or out of a gem.

The angle of refraction in the stone determines its RI. Gemstones with a high RI are more brilliant than those with a low RI. Diamond has an RI of 2.42; quartz, has an RI of 1.54-1.55. The RI of most gems is easily measured using a simple optical instrument known as a refractometer.

Some gemstones are singly refractive; they have only one refractive index, but most are doubly refractive; they have two different refractive indices. When a beam of light enters a doubly refractive gem, it is split into two beams, each travelling at a different speed and on a different path through the crystal.

Birefringence is a measurement of the difference between the two refractive indices in gems that are doubly refractive, and it ranges from a low of .003 to a high of .287.

The following chart lists the refractive indices for 215 varieties of gemstones.

Refractive Index Chart of all Gemstones
  Gemstone Refractive Index Double Refraction
1 Actinolite Cat's Eye 1.614 - 1.653 -
2 Agate 1.53 - 1.54 Yes
3 Agate Geode 1.53 - 1.54 -
4 Albite 1.528 - 1.542 -
5 Alexandrite 1.746 - 1.763 Yes
6 Almandine Garnet 1.77 - 1.82 -
7 Amazonite 1.522 - 1.53 Yes
8 Amber 1.539 - 1.545 -
9 Amblygonite 1.578 - 1.646 Yes
10 Amethyst 1.544 - 1.553 Yes
11 Amethyst Geode 1.544 - 1.553 Yes
12 Amethyst Geode Slice 1.53 - 1.54 -
13 Ametrine 1.544 - 1.553 -
14 Ammolite 1.52 - 1.68 Yes
15 Andalusite 1.627 - 1.649 Yes
16 Andesine Feldspar 1.56 - 1.57 -
17 Andesine Labradorite 1.551 - 1.56 Yes
18 Andradite Garnet 1.88 - 1.94 Yes
19 Apatite 1.628 - 1.649 Yes
20 Aquamarine 1.564 - 1.596 Yes
21 Aragonite 1.55 - 1.65 Yes
22 Aventurine 1.544 - 1.553 Yes
23 Axinite 1.656 - 1.704 Yes
24 Azotic Topaz 1.609 - 1.643 -
25 Azurite 1.72 - 1.848 Yes
26 Barite 1.634 - 1.648 Yes
27 Benitoite 1.75 - 1.8 Yes
28 Beryl 1.562 - 1.602 Yes
29 Black Opal 1.37 - 1.52 -
30 Bloodstone 1.53 - 1.54 -
31 Boulder Opal 1.37 - 1.52 -
32 Calcite 1.486 - 1.658 Yes
33 Carnelian 1.53 - 1.54 Yes
34 Cassiterite 1.997 - 2.098 Yes
35 Cat's Eye Apatite 1.628 - 1.649 -
36 Cat's Eye Aquamarine 1.564 - 1.596 Yes
37 Cat's Eye Augite 1.671 - 1.774 -
38 Cat's Eye Beryl 1.562 - 1.602 Yes
39 Cat's Eye Diaspore 1.702 - 1.75 Yes
40 Cat's Eye Moonstone 1.518 - 1.526 Yes
41 Cat's Eye Opal 1.37 - 1.52 -
42 Cat's Eye Scapolite 1.54 - 1.579 Yes
43 Cat's Eye Tourmaline 1.614 - 1.666 -
44 Cavansite 1.542 - 1.551 -
45 Chalcedony 1.53 - 1.54 Yes
46 Charoite 1.55 - 1.561 Yes
47 Chocolate Opal 1.37 - 1.52 -
48 Chrome Diopside 1.664 - 1.73 Yes
49 Chrome Tourmaline 1.614 - 1.666 Yes
50 Chrysoberyl 1.746 - 1.763 Yes
51 Chrysoberyl Cat's Eye 1.746 - 1.763 Yes
52 Chrysocolla 1.469 - 1.57 Yes
53 Chrysoprase 1.53 - 1.54 Yes
54 Cinnabar 2.905 - 3.256 Yes
55 Citrine 1.544 - 1.553 Yes
56 Citrine Geode 1.544 - 1.553 Yes
57 Clinohumite 1.629 - 1.674 Yes
58 Color-Change Diaspore 1.702 - 1.75 Yes
59 Color-Change Fluorite 1.434 -
60 Color-Change Garnet 1.73 - 1.756 -
61 Color-Change Sapphire 1.762 - 1.788 Yes
62 Coral 1.486 - 1.658 Yes
63 Crocoite 2.29 - 2.66 Yes
64 Cuprite 2.849 -
65 Danburite 1.63 - 1.636 Yes
66 Demantoid Garnet 1.88 - 1.94 -
67 Dendritic Agate 1.53 - 1.54 -
68 Dendritic Chalcedony 1.53 - 1.54 -
69 Diamond 2.417 - 2.419 -
70 Dolomite 1.679 - 1.681 Yes
71 Druzy Amethyst 1.544 - 1.553 -
72 Druzy Azurite 1.72 - 1.848 -
73 Druzy Citrine 1.544 - 1.553 -
74 Druzy Variscite 1.563 - 1.594 -
75 Dumortierite Quartz 1.678 - 1.689 -
76 Ekanite 1.568 - 1.58 Yes
77 Emerald 1.565 - 1.602 Yes
78 Enstatite 1.65 - 1.68 Yes
79 Epidote 1.729 - 1.768 Yes
80 Euclase 1.652 - 1.671 Yes
81 Eudialyte 1.606 - 1.613 Yes
82 Fire Agate 1.53 - 1.54 Yes
83 Fire Opal 1.37 - 1.52 -
84 Fluorite 1.434 -
85 Fossil Coral 1.53 - 1.54 -
86 Garnet 1.77 - 1.82 -
87 Gaspeite 1.61 - 1.81 Yes
88 Golden Beryl 1.562 - 1.602 Yes
89 Goshenite 1.562 - 1.602 Yes
90 Grandidierite 1.59 - 1.623 -
91 Grossularite Garnet 1.734 - 1.759 -
92 Hackmanite 1.48 -
93 Hambergite 1.553 - 1.628 Yes
94 Hawk's Eye 1.534 - 1.54 -
95 Hematite 2.94 - 3.22 Yes
96 Hemimorphite 1.614 - 1.636 Yes
97 Hemimorphite Druzy 1.614 - 1.636 -
98 Hessonite Garnet 1.73 - 1.75 -
99 Hiddenite 1.66 - 1.681 Yes
100 Howlite 1.586 - 1.605 Yes
101 Hyalite Opal 1.37 - 1.52 -
102 Idocrase 1.7 - 1.723 Yes
103 Imperial Topaz 1.609 - 1.643 -
104 Iolite 1.542 - 1.578 Yes
105 Jade 1.6 - 1.627 -
106 Jadeite 1.6 - 1.627 Yes
107 Jasper 1.54 -
108 Jet 1.64 - 1.68 -
109 Kornerupine 1.66 - 1.699 Yes
110 Kunzite 1.66 - 1.681 Yes
111 Kyanite 1.71 - 1.734 Yes
112 Labradorite 1.559 - 1.57 -
113 Lapis Lazuli 1.5 -
114 Larimar 1.595 - 1.645 -
115 Lazulite 1.637 - 1.663 Yes
116 Legrandite 1.675 - 1.74 Yes
117 Lepidolite 1.525 - 1.586 Yes
118 Malachite 1.655 - 1.909 Yes
119 Malaya Garnet 1.742 - 1.78 -
120 Mali Garnet 1.734 - 1.759 -
121 Maw-Sit-Sit 1.52 - 1.74 -
122 Melanite 1.88 - 1.94 -
123 Moldavite 1.48 - 1.54 -
124 Moonstone 1.518 - 1.526 Yes
125 Morganite 1.562 - 1.602 Yes
126 Moss Agate 1.53 - 1.54 Yes
127 Moss Opal 1.37 - 1.52 -
128 Mother of Pearl 1.53 - 1.69 -
129 Mystic Quartz 1.544 - 1.553 Yes
130 Mystic Topaz 1.609 - 1.643 -
131 Nephrite Jade 1.6 - 1.627 Yes
132 Nuummite 1.635 - 1.663 -
133 Obsidian 1.45 - 1.55 -
134 Omphacite Jade 1.662 - 1.723 Yes
135 Onyx 1.544 - 1.553 Yes
136 Opal 1.37 - 1.52 -
137 Opal Doublet 1.37 - 1.52 -
138 Opal in Matrix 1.37 - 1.52 -
139 Orthoclase 1.518 - 1.53 Yes
140 Paraiba Tourmaline 1.614 - 1.666 Yes
141 Peanut Wood 1.54 -
142 Pearl 1.52 - 1.69 Yes
143 Peridot 1.65 - 1.703 Yes
144 Pezzottaite 1.601 - 1.62 -
145 Pietersite 1.544 - 1.553 -
146 Prasiolite 1.544 - 1.553 Yes
147 Prehnite 1.611 - 1.669 Yes
148 Proustite 3.087 - 3.088 Yes
149 Psilomelane 2.11 - 2.26 -
150 Psilomelane Dendrite 2.11 - 2.26 -
151 Pyrite 1.73 - 1.838 -
152 Pyrope Garnet 1.72 - 1.756 -
153 Quartz 1.544 - 1.553 -
154 Quartz Cat's Eye 1.534 - 1.54 -
155 Quartz With Hedenbergite 1.544 - 1.553 -
156 Quartz With Marcasite 1.544 - 1.553 -
157 Rainbow Moonstone 1.518 - 1.526 Yes
158 Rainbow Pyrite 1.73 - 1.838 -
159 Realgar 2.538 - 2.704 -
160 Rhodochrosite 1.6 - 1.82 Yes
161 Rhodolite Garnet 1.72 - 1.76 -
162 Rhodonite 1.716 - 1.752 Yes
163 Rose Quartz 1.544 - 1.553 Yes
164 Rubellite Tourmaline 1.614 - 1.666 Yes
165 Ruby 1.762 - 1.778 Yes
166 Ruby in Fuchsite 1.552 - 1.615 -
167 Ruby-Zoisite 1.691 - 1.7 Yes
168 Rutile Quartz 1.544 - 1.553 -
169 Rutile Topaz 1.609 - 1.643 Yes
170 Sapphire 1.762 - 1.778 Yes
171 Sardonyx 1.53 - 1.543 -
172 Scapolite 1.54 - 1.579 Yes
173 Scolecite 1.507 - 1.525 Yes
174 Selenite 1.519 - 1.523 -
175 Seraphinite 1.576 - 1.599 Yes
176 Serpentine 1.56 - 1.571 Yes
177 Shattuckite 1.753 - 1.815 Yes
178 Sillimanite 1.655 - 1.684 Yes
179 Sillimanite Cat's Eye 1.655 - 1.684 Yes
180 Smithsonite 1.621 - 1.849 Yes
181 Smoky Quartz 1.544 - 1.553 Yes
182 Snowflake Obsidian 1.45 - 1.55 -
183 Sodalite 1.48 -
184 Spectrolite 1.559 - 1.57 -
185 Spessartite Garnet 1.79 - 1.82 -
186 Sphalerite 2.368 - 2.371 -
187 Sphene 1.843 - 2.11 Yes
188 Spinel 1.712 - 1.762 -
189 Spodumene 1.66 - 1.681 Yes
190 Star Diopside 1.664 - 1.73 Yes
191 Star Garnet 1.72 - 1.756 -
192 Star Lemon Quartz 1.544 - 1.553 -
193 Star Moonstone 1.518 - 1.526 Yes
194 Star Rose Quartz 1.53 - 1.54 -
195 Star Ruby 1.762 - 1.778 -
196 Star Sapphire 1.762 - 1.778 -
197 Star Sunstone 1.525 - 1.548 Yes
198 Strawberry Quartz 1.544 - 1.553 Yes
199 Sugilite 1.607 - 1.611 Yes
200 Sugilite Doublet 1.607 - 1.611 -
201 Sunstone 1.525 - 1.548 Yes
202 Tanzanite 1.691 - 1.7 Yes
203 Tashmarine Diopside 1.664 - 1.73 Yes
204 Tiger's Eye 1.534 - 1.54 -
205 Tiger's Eye Matrix 1.534 - 1.54 -
206 Topaz 1.609 - 1.643 Yes
207 Tourmaline 1.614 - 1.666 Yes
208 Tremolite-Hexagonite 1.56 - 1.643 -
209 Tsavorite Garnet 1.734 - 1.759 -
210 Turquoise 1.61 - 1.65 Yes
211 Uvarovite Garnet Drusy 1.865 -
212 Variscite 1.563 - 1.594 Yes
213 Verdite 1.552 - 1.576 -
214 Vivianite 1.579 - 1.656 Yes
215 Zircon 1.81 - 2.024 Yes

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  • Ekanite

    Ekanite Gemstones
    Refractive Index 1.568 - 1.58
    Double Refraction Yes
    Birefringence None

  • Emerald

    Emerald Gemstones
    Refractive Index 1.565 - 1.602
    Double Refraction Yes
    Birefringence 0.006

    Emerald Information

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  • Enstatite

    Enstatite Gemstones
    Refractive Index 1.65 - 1.68
    Double Refraction Yes
    Birefringence +0.009 to 0.012

    Enstatite Information

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  • Epidote

    Epidote Gemstones
    Refractive Index 1.729 - 1.768
    Double Refraction Yes
    Birefringence 0.015 to 0.049

    Epidote Information

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  • Euclase

    Euclase Gemstones
    Refractive Index 1.652 - 1.671
    Double Refraction Yes
    Birefringence 0.019

  • Eudialyte

    Eudialyte Gemstones
    Refractive Index 1.606 - 1.613
    Double Refraction Yes
    Birefringence 0.004

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Enlarged Gemstone Image