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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.
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 |
A
Refractive Index | 1.614 - 1.653 |
Double Refraction | - |
Birefringence | None |
Actinolite Cat's Eye Information
Shop Actinolite Cat's Eye
Refractive Index | 1.53 - 1.54 |
Double Refraction | Yes |
Birefringence | up to 0.004 |
Agate Information
Shop Agate
Refractive Index | 1.53 - 1.54 |
Double Refraction | - |
Birefringence | up to 0.004 |
Agate Geode Information
Shop Agate Geode
Refractive Index | 1.528 - 1.542 |
Double Refraction | - |
Birefringence | 0.010 |
Albite Information
Refractive Index | 1.746 - 1.763 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.010 |
Alexandrite Information
Shop Alexandrite
Refractive Index | 1.77 - 1.82 |
Double Refraction | - |
Birefringence | None |
Almandine Garnet Information
Shop Almandine Garnet
Refractive Index | 1.522 - 1.53 |
Double Refraction | Yes |
Birefringence | 0.008 |
Amazonite Information
Shop Amazonite
Refractive Index | 1.539 - 1.545 |
Double Refraction | - |
Birefringence | None |
Amber Information
Shop Amber
Refractive Index | 1.578 - 1.646 |
Double Refraction | Yes |
Birefringence | None |
Amblygonite Information
Shop Amblygonite
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Amethyst Information
Shop Amethyst
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Amethyst Geode Information
Shop Amethyst Geode
Refractive Index | 1.53 - 1.54 |
Double Refraction | - |
Birefringence | up to 0.004 |
Amethyst Geode Slice Information
Shop Amethyst Geode Slice
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | 0.009 |
Ametrine Information
Shop Ametrine
Refractive Index | 1.52 - 1.68 |
Double Refraction | Yes |
Birefringence | 0.155 |
Ammolite Information
Shop Ammolite
Refractive Index | 1.627 - 1.649 |
Double Refraction | Yes |
Birefringence | 0.007 to 0.013 |
Andalusite Information
Shop Andalusite
Refractive Index | 1.56 - 1.57 |
Double Refraction | - |
Birefringence | 0.009 |
Andesine Feldspar Information
Refractive Index | 1.551 - 1.56 |
Double Refraction | Yes |
Birefringence | 0..0008 |
Andesine Labradorite Information
Shop Andesine Labradorite
Refractive Index | 1.88 - 1.94 |
Double Refraction | Yes |
Birefringence | None |
Andradite Garnet Information
Refractive Index | 1.628 - 1.649 |
Double Refraction | Yes |
Birefringence | 0.002 to 0.006 |
Apatite Information
Shop Apatite
Refractive Index | 1.564 - 1.596 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.005 |
Aquamarine Information
Shop Aquamarine
Refractive Index | 1.55 - 1.65 |
Double Refraction | Yes |
Birefringence | 0.155 |
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Aventurine Information
Shop Aventurine
Refractive Index | 1.656 - 1.704 |
Double Refraction | Yes |
Birefringence | 0.010 to 0.012 |
Axinite Information
Shop Axinite
Refractive Index | 1.609 - 1.643 |
Double Refraction | - |
Birefringence | 0.008 to 0.016 |
Azotic Topaz Information
Shop Azotic Topaz
Refractive Index | 1.72 - 1.848 |
Double Refraction | Yes |
Birefringence | 0.108 to 0.110 |
Azurite Information
Shop Azurite
B
Refractive Index | 1.634 - 1.648 |
Double Refraction | Yes |
Birefringence | 0.012 |
Refractive Index | 1.75 - 1.8 |
Double Refraction | Yes |
Birefringence | 0.047 |
Benitoite Information
Refractive Index | 1.562 - 1.602 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.010 |
Beryl Information
Shop Beryl
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Black Opal Information
Shop Black Opal
Refractive Index | 1.53 - 1.54 |
Double Refraction | - |
Birefringence | up to 0.004 |
Bloodstone Information
Shop Bloodstone
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Boulder Opal Information
Shop Boulder Opal
C
Refractive Index | 1.486 - 1.658 |
Double Refraction | Yes |
Birefringence | 0.172 |
Calcite Information
Shop Calcite
Refractive Index | 1.53 - 1.54 |
Double Refraction | Yes |
Birefringence | up to 0.004 |
Carnelian Information
Shop Carnelian
Refractive Index | 1.997 - 2.098 |
Double Refraction | Yes |
Birefringence | 0.096 to 0.098 |
Cassiterite Information
Shop Cassiterite
Refractive Index | 1.628 - 1.649 |
Double Refraction | - |
Birefringence | 0.002 to 0.006 |
Cat's Eye Apatite Information
Shop Cat's Eye Apatite
Refractive Index | 1.564 - 1.596 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.005 |
Cat's Eye Aquamarine Information
Shop Cat's Eye Aquamarine
Refractive Index | 1.671 - 1.774 |
Double Refraction | - |
Birefringence | 0.026 - 0.039 |
Shop Cat's Eye Augite
Refractive Index | 1.562 - 1.602 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.010 |
Cat's Eye Beryl Information
Shop Cat's Eye Beryl
Refractive Index | 1.702 - 1.75 |
Double Refraction | Yes |
Birefringence | 0.048 |
Cat's Eye Diaspore Information
Shop Cat's Eye Diaspore
Refractive Index | 1.518 - 1.526 |
Double Refraction | Yes |
Birefringence | None |
Cat's Eye Moonstone Information
Shop Cat's Eye Moonstone
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Cat's Eye Opal Information
Shop Cat's Eye Opal
Refractive Index | 1.54 - 1.579 |
Double Refraction | Yes |
Birefringence | 0.006 to 0.037 |
Cat's Eye Scapolite Information
Shop Cat's Eye Scapolite
Refractive Index | 1.614 - 1.666 |
Double Refraction | - |
Birefringence | 0.014 to 0.032 |
Cat's Eye Tourmaline Information
Shop Cat's Eye Tourmaline
Refractive Index | 1.542 - 1.551 |
Double Refraction | - |
Birefringence | 0.009 |
Refractive Index | 1.53 - 1.54 |
Double Refraction | Yes |
Birefringence | up to 0.004 |
Chalcedony Information
Shop Chalcedony
Refractive Index | 1.55 - 1.561 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.009 |
Charoite Information
Shop Charoite
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Chocolate Opal Information
Shop Chocolate Opal
Refractive Index | 1.664 - 1.73 |
Double Refraction | Yes |
Birefringence | 0.024 to 0.031 |
Chrome Diopside Information
Shop Chrome Diopside
Refractive Index | 1.614 - 1.666 |
Double Refraction | Yes |
Birefringence | 0.014 to 0.032 |
Chrome Tourmaline Information
Shop Chrome Tourmaline
Refractive Index | 1.746 - 1.763 |
Double Refraction | Yes |
Birefringence | 0.007 to 0.011 |
Chrysoberyl Information
Shop Chrysoberyl
Refractive Index | 1.746 - 1.763 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.010 |
Chrysoberyl Cat's Eye Information
Shop Chrysoberyl Cat's Eye
Refractive Index | 1.469 - 1.57 |
Double Refraction | Yes |
Birefringence | 0.023 to 0.040 |
Chrysocolla Information
Shop Chrysocolla
Refractive Index | 1.53 - 1.54 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.009 |
Chrysoprase Information
Shop Chrysoprase
Refractive Index | 2.905 - 3.256 |
Double Refraction | Yes |
Birefringence | 0.351 |
Cinnabar Information
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Citrine Information
Shop Citrine
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Citrine Geode Information
Shop Citrine Geode
Refractive Index | 1.629 - 1.674 |
Double Refraction | Yes |
Birefringence | 0.029 - 0.045 |
Clinohumite Information
Shop Clinohumite
Refractive Index | 1.702 - 1.75 |
Double Refraction | Yes |
Birefringence | 0.048 |
Color-Change Diaspore Information
Shop Color-Change Diaspore
Refractive Index | 1.434 |
Double Refraction | - |
Birefringence | None |
Color-Change Fluorite Information
Shop Color-Change Fluorite
Refractive Index | 1.73 - 1.756 |
Double Refraction | - |
Birefringence | None |
Color-Change Garnet Information
Shop Color-Change Garnet
Refractive Index | 1.762 - 1.788 |
Double Refraction | Yes |
Birefringence | 0.008 |
Color-Change Sapphire Information
Shop Color-Change Sapphire
Refractive Index | 1.486 - 1.658 |
Double Refraction | Yes |
Birefringence | White and red: 0.160 to 0.172 |
Coral Information
Shop Coral
Refractive Index | 2.29 - 2.66 |
Double Refraction | Yes |
Birefringence | 0.370 |
Refractive Index | 2.849 |
Double Refraction | - |
Birefringence | None |
D
Refractive Index | 1.63 - 1.636 |
Double Refraction | Yes |
Birefringence | 0.006 to 0.008 |
Danburite Information
Shop Danburite
Refractive Index | 1.88 - 1.94 |
Double Refraction | - |
Birefringence | None |
Demantoid Garnet Information
Shop Demantoid Garnet
Refractive Index | 1.53 - 1.54 |
Double Refraction | - |
Birefringence | up to 0.004 |
Dendritic Agate Information
Shop Dendritic Agate
Refractive Index | 1.53 - 1.54 |
Double Refraction | - |
Birefringence | up to 0.004 |
Dendritic Chalcedony Information
Shop Dendritic Chalcedony
Refractive Index | 2.417 - 2.419 |
Double Refraction | - |
Birefringence | None |
Diamond Information
Shop Diamond
Refractive Index | 1.679 - 1.681 |
Double Refraction | Yes |
Birefringence | 0.179-0.181 |
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | None |
Druzy Amethyst Information
Shop Druzy Amethyst
Refractive Index | 1.72 - 1.848 |
Double Refraction | - |
Birefringence | 0.108 to 0.110 |
Druzy Azurite Information
Shop Druzy Azurite
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | None |
Druzy Citrine Information
Shop Druzy Citrine
Refractive Index | 1.563 - 1.594 |
Double Refraction | - |
Birefringence | None |
Druzy Variscite Information
Shop Druzy Variscite
Refractive Index | 1.678 - 1.689 |
Double Refraction | - |
Birefringence | 0.015 to 0.037 |
Dumortierite Quartz Information
Shop Dumortierite Quartz
E
Refractive Index | 1.568 - 1.58 |
Double Refraction | Yes |
Birefringence | None |
Refractive Index | 1.565 - 1.602 |
Double Refraction | Yes |
Birefringence | 0.006 |
Emerald Information
Shop Emerald
Refractive Index | 1.65 - 1.68 |
Double Refraction | Yes |
Birefringence | +0.009 to 0.012 |
Enstatite Information
Shop Enstatite
Refractive Index | 1.729 - 1.768 |
Double Refraction | Yes |
Birefringence | 0.015 to 0.049 |
Epidote Information
Shop Epidote
Refractive Index | 1.652 - 1.671 |
Double Refraction | Yes |
Birefringence | 0.019 |
Refractive Index | 1.606 - 1.613 |
Double Refraction | Yes |
Birefringence | 0.004 |
F
Refractive Index | 1.53 - 1.54 |
Double Refraction | Yes |
Birefringence | up to 0.004 |
Fire Agate Information
Shop Fire Agate
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Fire Opal Information
Shop Fire Opal
Refractive Index | 1.434 |
Double Refraction | - |
Birefringence | None |
Fluorite Information
Shop Fluorite
Refractive Index | 1.53 - 1.54 |
Double Refraction | - |
Birefringence | up to 0.004 |
Fossil Coral Information
Shop Fossil Coral
G
Refractive Index | 1.77 - 1.82 |
Double Refraction | - |
Birefringence | None |
Garnet Information
Shop Garnet
Refractive Index | 1.61 - 1.81 |
Double Refraction | Yes |
Birefringence | 0.22 |
Gaspeite Information
Shop Gaspeite
Refractive Index | 1.562 - 1.602 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.010 |
Golden Beryl Information
Shop Golden Beryl
Refractive Index | 1.562 - 1.602 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.010 |
Goshenite Information
Shop Goshenite
Refractive Index | 1.59 - 1.623 |
Double Refraction | - |
Birefringence | 0.033 - 0.037 |
Grandidierite Information
Shop Grandidierite
Refractive Index | 1.734 - 1.759 |
Double Refraction | - |
Birefringence | None |
Grossularite Garnet Information
Shop Grossularite Garnet
H
Refractive Index | 1.48 |
Double Refraction | - |
Birefringence | None |
Hackmanite Information
Shop Hackmanite
Refractive Index | 1.553 - 1.628 |
Double Refraction | Yes |
Birefringence | 0.0072 |
Hambergite Information
Shop Hambergite
Refractive Index | 1.534 - 1.54 |
Double Refraction | - |
Birefringence | None |
Hawk's Eye Information
Shop Hawk's Eye
Refractive Index | 2.94 - 3.22 |
Double Refraction | Yes |
Birefringence | 0.287 |
Hematite Information
Shop Hematite
Refractive Index | 1.614 - 1.636 |
Double Refraction | Yes |
Birefringence | 0.022 |
Hemimorphite Information
Shop Hemimorphite
Refractive Index | 1.614 - 1.636 |
Double Refraction | - |
Birefringence | +0.022 |
Hemimorphite Druzy Information
Shop Hemimorphite Druzy
Refractive Index | 1.73 - 1.75 |
Double Refraction | - |
Birefringence | None |
Hessonite Garnet Information
Shop Hessonite Garnet
Refractive Index | 1.66 - 1.681 |
Double Refraction | Yes |
Birefringence | 0.014 to 0.016 |
Hiddenite Information
Shop Hiddenite
Refractive Index | 1.586 - 1.605 |
Double Refraction | Yes |
Birefringence | 0.019 |
Howlite Information
Shop Howlite
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Hyalite Opal Information
Shop Hyalite Opal
I
Refractive Index | 1.7 - 1.723 |
Double Refraction | Yes |
Birefringence | 0.002 to 0.012 |
Idocrase Information
Shop Idocrase
Refractive Index | 1.609 - 1.643 |
Double Refraction | - |
Birefringence | 0.008 to 0.016 |
Imperial Topaz Information
Shop Imperial Topaz
Refractive Index | 1.542 - 1.578 |
Double Refraction | Yes |
Birefringence | 0.008 to 0.012 |
Iolite Information
Shop Iolite
J
Refractive Index | 1.6 - 1.627 |
Double Refraction | - |
Birefringence | 0.027 |
Jade Information
Shop Jade
Refractive Index | 1.6 - 1.627 |
Double Refraction | Yes |
Birefringence | 0.027 |
Jadeite Information
Shop Jadeite
Refractive Index | 1.54 |
Double Refraction | - |
Birefringence | None |
Jasper Information
Shop Jasper
Refractive Index | 1.64 - 1.68 |
Double Refraction | - |
Birefringence | None |
Jet Information
K
Refractive Index | 1.66 - 1.699 |
Double Refraction | Yes |
Birefringence | None |
Kornerupine Information
Shop Kornerupine
Refractive Index | 1.66 - 1.681 |
Double Refraction | Yes |
Birefringence | 0.014 to 0.016 |
Kunzite Information
Shop Kunzite
Refractive Index | 1.71 - 1.734 |
Double Refraction | Yes |
Birefringence | 0.0015 to 0.033 |
Kyanite Information
Shop Kyanite
L
Refractive Index | 1.559 - 1.57 |
Double Refraction | - |
Birefringence | 0.008 to 0.010 |
Labradorite Information
Shop Labradorite
Refractive Index | 1.5 |
Double Refraction | - |
Birefringence | None |
Lapis Lazuli Information
Shop Lapis Lazuli
Refractive Index | 1.595 - 1.645 |
Double Refraction | - |
Birefringence | 0.038 |
Larimar Information
Shop Larimar
Refractive Index | 1.637 - 1.663 |
Double Refraction | Yes |
Birefringence | 0.033 - 0.037 |
Refractive Index | 1.675 - 1.74 |
Double Refraction | Yes |
Birefringence | 0.060 |
Refractive Index | 1.525 - 1.586 |
Double Refraction | Yes |
Birefringence | 0.0290 to 0.0380 |
Lepidolite Information
Shop Lepidolite
M
Refractive Index | 1.655 - 1.909 |
Double Refraction | Yes |
Birefringence | 0.254 |
Malachite Information
Shop Malachite
Refractive Index | 1.742 - 1.78 |
Double Refraction | - |
Birefringence | None |
Malaya Garnet Information
Shop Malaya Garnet
Refractive Index | 1.734 - 1.759 |
Double Refraction | - |
Birefringence | None |
Mali Garnet Information
Shop Mali Garnet
Refractive Index | 1.52 - 1.74 |
Double Refraction | - |
Birefringence | 0.0150 to 0.020 |
Maw-Sit-Sit Information
Shop Maw-Sit-Sit
Refractive Index | 1.88 - 1.94 |
Double Refraction | - |
Birefringence | None |
Melanite Information
Shop Melanite
Refractive Index | 1.48 - 1.54 |
Double Refraction | - |
Birefringence | None |
Moldavite Information
Shop Moldavite
Refractive Index | 1.518 - 1.526 |
Double Refraction | Yes |
Birefringence | 0.008 |
Moonstone Information
Shop Moonstone
Refractive Index | 1.562 - 1.602 |
Double Refraction | Yes |
Birefringence | 0.004 to 0.010 |
Morganite Information
Shop Morganite
Refractive Index | 1.53 - 1.54 |
Double Refraction | Yes |
Birefringence | up to 0.004 |
Moss Agate Information
Shop Moss Agate
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Moss Opal Information
Shop Moss Opal
Refractive Index | 1.53 - 1.69 |
Double Refraction | - |
Birefringence | None |
Mother of Pearl Information
Shop Mother of Pearl
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Mystic Quartz Information
Shop Mystic Quartz
Refractive Index | 1.609 - 1.643 |
Double Refraction | - |
Birefringence | 0.008 to 0.016 |
Mystic Topaz Information
Shop Mystic Topaz
N
Refractive Index | 1.6 - 1.627 |
Double Refraction | Yes |
Birefringence | 0.027 |
Nephrite Jade Information
Shop Nephrite Jade
Refractive Index | 1.635 - 1.663 |
Double Refraction | - |
Birefringence | 0.022 |
Nuummite Information
Shop Nuummite
O
Refractive Index | 1.45 - 1.55 |
Double Refraction | - |
Birefringence | None |
Obsidian Information
Shop Obsidian
Refractive Index | 1.662 - 1.723 |
Double Refraction | Yes |
Birefringence | None |
Omphacite Jade Information
Shop Omphacite Jade
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | up to 0.004 |
Onyx Information
Shop Onyx
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Opal Information
Shop Opal
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Opal Doublet Information
Shop Opal Doublet
Refractive Index | 1.37 - 1.52 |
Double Refraction | - |
Birefringence | None |
Opal in Matrix Information
Shop Opal in Matrix
Refractive Index | 1.518 - 1.53 |
Double Refraction | Yes |
Birefringence | 0.008 |
Orthoclase Information
Shop Orthoclase
P
Refractive Index | 1.614 - 1.666 |
Double Refraction | Yes |
Birefringence | 0.014 to 0.032 |
Paraiba Tourmaline Information
Shop Paraiba Tourmaline
Refractive Index | 1.54 |
Double Refraction | - |
Birefringence | None |
Shop Peanut Wood
Refractive Index | 1.52 - 1.69 |
Double Refraction | Yes |
Birefringence | 0.156 |
Pearl Information
Shop Pearl
Refractive Index | 1.65 - 1.703 |
Double Refraction | Yes |
Birefringence | 0.036 to 0.038 |
Peridot Information
Shop Peridot
Refractive Index | 1.601 - 1.62 |
Double Refraction | - |
Birefringence | None |
Pezzottaite Information
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | 0.009 |
Pietersite Information
Shop Pietersite
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Refractive Index | 1.611 - 1.669 |
Double Refraction | Yes |
Birefringence | 0.0021 to 0.039 |
Prehnite Information
Shop Prehnite
Refractive Index | 3.087 - 3.088 |
Double Refraction | Yes |
Birefringence | 0.295 - 0.296 |
Refractive Index | 2.11 - 2.26 |
Double Refraction | - |
Birefringence | N/A |
Shop Psilomelane
Refractive Index | 2.11 - 2.26 |
Double Refraction | - |
Birefringence | None |
Refractive Index | 1.73 - 1.838 |
Double Refraction | - |
Birefringence | None |
Pyrite Information
Shop Pyrite
Refractive Index | 1.72 - 1.756 |
Double Refraction | - |
Birefringence | None |
Pyrope Garnet Information
Shop Pyrope Garnet
Q
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | 0.009 |
Quartz Information
Shop Quartz
Refractive Index | 1.534 - 1.54 |
Double Refraction | - |
Birefringence | None |
Quartz Cat's Eye Information
Shop Quartz Cat's Eye
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | 0.009 |
Quartz With Hedenbergite Information
Shop Quartz With Hedenbergite
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | 0.009 |
Quartz With Marcasite Information
Shop Quartz With Marcasite
R
Refractive Index | 1.518 - 1.526 |
Double Refraction | Yes |
Birefringence | 0.008 |
Rainbow Moonstone Information
Shop Rainbow Moonstone
Refractive Index | 1.73 - 1.838 |
Double Refraction | - |
Birefringence | None |
Rainbow Pyrite Information
Shop Rainbow Pyrite
Refractive Index | 2.538 - 2.704 |
Double Refraction | - |
Birefringence | 0.166 |
Refractive Index | 1.6 - 1.82 |
Double Refraction | Yes |
Birefringence | 0.208 to 0.220 |
Rhodochrosite Information
Shop Rhodochrosite
Refractive Index | 1.72 - 1.76 |
Double Refraction | - |
Birefringence | None |
Rhodolite Garnet Information
Shop Rhodolite Garnet
Refractive Index | 1.716 - 1.752 |
Double Refraction | Yes |
Birefringence | 0.010 to 0.014 |
Rhodonite Information
Shop Rhodonite
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Rose Quartz Information
Shop Rose Quartz
Refractive Index | 1.614 - 1.666 |
Double Refraction | Yes |
Birefringence | 0.014 to 0.032 |
Rubellite Tourmaline Information
Shop Rubellite Tourmaline
Refractive Index | 1.762 - 1.778 |
Double Refraction | Yes |
Birefringence | 0.008 |
Ruby Information
Shop Ruby
Refractive Index | 1.552 - 1.615 |
Double Refraction | - |
Birefringence | 0.036-0.043 |
Ruby in Fuchsite Information
Shop Ruby in Fuchsite
Refractive Index | 1.691 - 1.7 |
Double Refraction | Yes |
Birefringence | 0.009 |
Ruby-Zoisite Information
Shop Ruby-Zoisite
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | 0.009 |
Rutile Quartz Information
Shop Rutile Quartz
Refractive Index | 1.609 - 1.643 |
Double Refraction | Yes |
Birefringence | 0.008 to 0.016 |
Rutile Topaz Information
Shop Rutile Topaz
S
Refractive Index | 1.762 - 1.778 |
Double Refraction | Yes |
Birefringence | 0.008 |
Sapphire Information
Shop Sapphire
Refractive Index | 1.53 - 1.543 |
Double Refraction | - |
Birefringence | None |
Sardonyx Information
Refractive Index | 1.54 - 1.579 |
Double Refraction | Yes |
Birefringence | 0.006 to 0.037 |
Scapolite Information
Shop Scapolite
Refractive Index | 1.507 - 1.525 |
Double Refraction | Yes |
Birefringence | 0.007 - 0.012 |
Shop Scolecite
Refractive Index | 1.519 - 1.523 |
Double Refraction | - |
Birefringence | 0.0090-0.0100 |
Selenite Information
Refractive Index | 1.576 - 1.599 |
Double Refraction | Yes |
Birefringence | 0,005 to 0.011 |
Seraphinite Information
Shop Seraphinite
Refractive Index | 1.56 - 1.571 |
Double Refraction | Yes |
Birefringence | 0.008 to 0.014 |
Serpentine Information
Shop Serpentine
Refractive Index | 1.753 - 1.815 |
Double Refraction | Yes |
Birefringence | None |
Refractive Index | 1.655 - 1.684 |
Double Refraction | Yes |
Birefringence | 0.016 |
Sillimanite Information
Shop Sillimanite
Refractive Index | 1.655 - 1.684 |
Double Refraction | Yes |
Birefringence | 0.014 to 0.021 |
Sillimanite Cat's Eye Information
Shop Sillimanite Cat's Eye
Refractive Index | 1.621 - 1.849 |
Double Refraction | Yes |
Birefringence | 0.228 |
Smithsonite Information
Shop Smithsonite
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Smoky Quartz Information
Shop Smoky Quartz
Refractive Index | 1.45 - 1.55 |
Double Refraction | - |
Birefringence | None |
Snowflake Obsidian Information
Shop Snowflake Obsidian
Refractive Index | 1.48 |
Double Refraction | - |
Birefringence | None |
Sodalite Information
Shop Sodalite
Refractive Index | 1.559 - 1.57 |
Double Refraction | - |
Birefringence | 0.008 - 0.010 |
Spectrolite Information
Shop Spectrolite
Refractive Index | 1.79 - 1.82 |
Double Refraction | - |
Birefringence | None |
Spessartite Garnet Information
Shop Spessartite Garnet
Refractive Index | 2.368 - 2.371 |
Double Refraction | - |
Birefringence | None |
Sphalerite Information
Shop Sphalerite
Refractive Index | 1.843 - 2.11 |
Double Refraction | Yes |
Birefringence | 0.100 to 0.192 |
Sphene Information
Shop Sphene
Refractive Index | 1.712 - 1.762 |
Double Refraction | - |
Birefringence | None |
Spinel Information
Shop Spinel
Refractive Index | 1.66 - 1.681 |
Double Refraction | Yes |
Birefringence | 0.014 to 0.016 |
Spodumene Information
Shop Spodumene
Refractive Index | 1.664 - 1.73 |
Double Refraction | Yes |
Birefringence | 0.024 to 0.031 |
Star Diopside Information
Shop Star Diopside
Refractive Index | 1.72 - 1.756 |
Double Refraction | - |
Birefringence | None |
Star Garnet Information
Shop Star Garnet
Refractive Index | 1.544 - 1.553 |
Double Refraction | - |
Birefringence | 0.009 |
Star Lemon Quartz Information
Shop Star Lemon Quartz
Refractive Index | 1.518 - 1.526 |
Double Refraction | Yes |
Birefringence | 0.008 |
Star Moonstone Information
Shop Star Moonstone
Refractive Index | 1.53 - 1.54 |
Double Refraction | - |
Birefringence | 0.009 |
Star Rose Quartz Information
Shop Star Rose Quartz
Refractive Index | 1.762 - 1.778 |
Double Refraction | - |
Birefringence | 0.008 |
Star Ruby Information
Shop Star Ruby
Refractive Index | 1.762 - 1.778 |
Double Refraction | - |
Birefringence | 0.008 |
Star Sapphire Information
Shop Star Sapphire
Refractive Index | 1.525 - 1.548 |
Double Refraction | Yes |
Birefringence | 0.010 |
Star Sunstone Information
Shop Star Sunstone
Refractive Index | 1.544 - 1.553 |
Double Refraction | Yes |
Birefringence | 0.009 |
Strawberry Quartz Information
Shop Strawberry Quartz
Refractive Index | 1.607 - 1.611 |
Double Refraction | Yes |
Birefringence | 0.001 to 0.004 |
Sugilite Information
Shop Sugilite
Refractive Index | 1.607 - 1.611 |
Double Refraction | - |
Birefringence | 0.001 to 0.004 |
Shop Sugilite Doublet
Refractive Index | 1.525 - 1.548 |
Double Refraction | Yes |
Birefringence | 0.010 |
Sunstone Information
Shop Sunstone
T
Refractive Index | 1.691 - 1.7 |
Double Refraction | Yes |
Birefringence | 0.009 |
Tanzanite Information
Shop Tanzanite
Refractive Index | 1.664 - 1.73 |
Double Refraction | Yes |
Birefringence | 0.024 to 0.031 |
Tashmarine Diopside Information
Shop Tashmarine Diopside
Refractive Index | 1.534 - 1.54 |
Double Refraction | - |
Birefringence | None |
Tiger's Eye Information
Shop Tiger's Eye
Refractive Index | 1.534 - 1.54 |
Double Refraction | - |
Birefringence | None |
Tiger's Eye Matrix Information
Shop Tiger's Eye Matrix
Refractive Index | 1.609 - 1.643 |
Double Refraction | Yes |
Birefringence | 0.008 to 0.016 |
Topaz Information
Shop Topaz
Refractive Index | 1.614 - 1.666 |
Double Refraction | Yes |
Birefringence | 0.014 to 0.032 |
Tourmaline Information
Shop Tourmaline
Refractive Index | 1.56 - 1.643 |
Double Refraction | - |
Birefringence | 0.017 to 0.027 |
Shop Tremolite-Hexagonite
Refractive Index | 1.734 - 1.759 |
Double Refraction | - |
Birefringence | None |
Tsavorite Garnet Information
Shop Tsavorite Garnet
Refractive Index | 1.61 - 1.65 |
Double Refraction | Yes |
Birefringence | 0.040 |
Turquoise Information
Shop Turquoise
U
Refractive Index | 1.865 |
Double Refraction | - |
Birefringence | None |
Uvarovite Garnet Drusy Information
Shop Uvarovite Garnet Drusy
V
Refractive Index | 1.563 - 1.594 |
Double Refraction | Yes |
Birefringence | 0.031 |
Variscite Information
Shop Variscite
Refractive Index | 1.552 - 1.576 |
Double Refraction | - |
Birefringence | None |
Verdite Information
Shop Verdite
Refractive Index | 1.579 - 1.656 |
Double Refraction | Yes |
Birefringence | 0.050-0.059 |
Z
Refractive Index | 1.81 - 2.024 |
Double Refraction | Yes |
Birefringence | 0.002 to 0.059 |
Zircon Information
Shop Zircon
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