Global Gemology - Rare Gems & Jewels
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REFRACTIVE INDEX CHART

Picture
Refraction is the bending of light as it passes through a gem.  The angle of refraction determines its refractive index, or RI.

Scroll down for a chart of over 100 gems and their corresponding RI.

GEM VARIETY
R.I.
BIREFRINGENCE
​Hematine
2.940 - 3.220
0.287
Moissanite
2.650 - 2.690
0.043
Diamond
2.417 - 2.419
None
Cubic Zirconia
2.15 - 2.18
None
Demantoid
1.88 - 1.94
None
Uvarovite
1.865
None
Zircon
1.810 - 2.024
0.002 - 0.059
Spessartine
1.790 - 1.820
None
Almandine
1.770 - 1.820
None
Ruby
1.762 - 1.778
0.008
Sapphire
1.762 - 1.778
0.008
Alexandrite
1.746 - 1.763
0.007 - 0.011
Chrysoberyl
1.746 - 1.763
0.007 - 0.011
Cat's Eye
1.746 - 1.763
0.007 - 0.011
Rhodolite
1.742 - 1.785
None
Color Change Garnet
1.742 - 1.780
​None
Tsavorite
1.734 - 1.759
None
Hessonite
1.730 - 1.757
None
Azurite
1.720 - 1.848
0.108 - 0.110
Pyrope
1.720 - 1.756
None
Spinel
1.712 - 1.782
None
Tanzanite
1.691 - 1.700
0.009
Diopside
1.664 - 1.730
0.024 - 0.031
Kunzite
1.660 - 1.681
0.014 - 0.016
Malachite
1.666 - 1.909
0.254
Jadeite
1.652 - 1.688
0.020
Peridot
1.650 - 1.703
0.036 - 0.038
Jet
1.640 - 1.680
None
Apatite
1.628 - 1.649
0.002 - 0.006
Andalusite
1.627 - 1.649
0.007 - 0.013
Tourmaline
1.614 - 1.666
0.014 - 0.032
Gaspeite
1.610 - 1.810
0.220
Turquoise
1.610 - 1.650
0.040
Topaz
1.609 - 1.643
0.009 - 0016
Sugilite
1.607 - 1.611
0.001 - 0.004
Rhodochrosite
1.600 - 1.820
0.208 - 0.220
Nephrite
1.600 - 1.627
0.027
Howlite
1.586 - 1.605
0.019
Emerald
1.565 - 1.602
0.005
Aquamarine
1.565 - 1.602
0.005
Morganite
1.562 - 1.605
0.004 - 0.010
Heliodor
1.562 - 1.605
0.004 - 0.010
Bixbite
1.562 - 1.605
0.004 - 0.010
Goshenite
1.562 - 1.605
0.004 - 0.010
Labradorite
1.559 - 1.570
0.008 - 0.010
Charoite
1.550 - 1.561
0.004 - 0.009
Amethyst
1.544 - 1.553
0.009
Aventurine
1.544 - 1.553
0.009
Ametrine
1.544 - 1.553
0.009
Citrine
1.544 - 1.553
0.009
Rock Crystal
1.544 - 1.553
0.009
Rose Quartz
1.544 - 1.553
0.009
Smoky Quartz
1.544 - 1.553
0.009
Iolite
1.542 - 1.578
0.008 - 0.012
Jasper
1.54
None
Amber
1.539 - 1.545
None
Agate
1.530 - 1.540
0.004 - 0.009
Bloodstone
1.530 - 1.540
0.004 - 0.009
Chalcedony
1.530 - 1.540
0.004 - 0.009
Carnelian
1.530 - 1.540
0.004 - 0.009
Chrysoprase
1.530 - 1.540
0.004 - 0.009
Onyx
1.530 - 1.540
0.004 - 0.009
Sunstone
1.525 - 1.548
0.010
Amazonite
1.522 - 1.530
0.008
Pearl
1.52 - 1.69
0.1.58
Moonstone
1.518 - 1.528
0.008
Lapis Lazuli
1.500
None
Coral
1.486 - 1.658 
0.160 - 0.172
Moldavite
1.48 - 1.54
None
Sodalite
1.48
None
Chrysocolla
1.46 - 1.57
0.023 - 0.040
Obsidian
1.45 - 1.55
None
Fluorite
1.434
None
Fire Opal
1.37 - 1.52
None
Opal
1.37 - 1.52
None
  • HOME
  • ABOUT
  • SHOP
  • SERVICES
    • APPRAISALS
    • EXPERT WITNESS TESTIMONY
    • SELL YOUR JEWELRY
  • GEMOLOGY
    • GEM ENCYCLOPEDIA
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  • JEWELRY EDUCATION
    • DIAMOND FACTS
    • JEWELER DIRECTORY
    • JEWELRY PERIODS
    • POCKET WATCHES
    • NATIVE AMERICAN JEWELRY
  • GLOSSARY