What is the index of refraction of diamond

Table of refraction of light of gemstones - index of refraction

The refractive index or the refraction of light of a gemstone is one of the most important properties or the most important signature of a gemstone. Measuring the index of refraction is one of the first steps in correctly identifying a gemstone. Gemstones that have identical or similar light refraction are then put to the test using additional methods.

If light passes from one medium (e.g. from the medium air) into another (e.g. into a precious stone), one can observe that the light beam is refracted. You probably know this phenomenon from your own experience: If you dip a spoon in a transparent glass with pure water, you get the impression as if the spoon was, so to speak, "kinked" at the point of entry into the water - this is precisely what is known as refraction of light. This light refraction effect is related to the fact that light in the air has a different speed than e.g. in the medium water or other aggregate forms. The change in speed has the effect that light beams that strike obliquely are deflected. The index of refraction is determined by dividing the sine value of the angle of incidence (= the angle between the perpendicular and the incident light beam) by the sine value of the angle of refraction (= the angle between the angle of incidence and the refracted light beam). The calculation of the refractive index is of particular importance because every mineral or gemstone and gemstone has constant values ​​- if a gemstone or gemstone cannot be clearly identified purely optically, the refractive index can be used to determine which gemstone it really is , with the exception of types of gemstone with a similar refractive index. In order to precisely determine the refractive index, experts and gemologists often use a special device, the so-called refractometer. In most cases, the refraction of light is called "n", the ratio of the speed of light in the medium of air to the speed of light in the gem.

The refractive index or the refractive index is the ratio between the speed of light in air and the speed of light in a transparent material such as a gemstone. If light from the air shines into a transparent material, a gemstone, at an angle of incidence other than 90 degrees, it is deflected to a different angle (the coincidence angle) depending on the refractive index or light refractive index of the material or gemstone. Genuine gemstones with a higher refraction generally shine more strongly than the gemstones with a lower refraction because more light is reflected back to the viewer from the top or crown of the gem. Diamonds have a light refraction of approx. 2.4 and are therefore quite "sparkling". Quartz gemstones, on the other hand, have a refractive index of approx. 1.53 - 1.55, whereas these gemstones do not "sparkle" as much as a diamond. The refractive index of most gemstones can easily be measured by a layperson using a simple optical device called a refractometer, also known as a refractometer.

Some gemstones are easy to break; they only have one index of refraction. Other gemstones - most of the known gemstones - have two different refractions of light. When a ray of light hits a double refracting gem, it is split into two rays, each going through the gem or crystal at a different speed and by a different route. Birefringence is the measure of the difference between two refractive indices in double refracting gemstones. Birefringence is the result of the difference between the highest and lowest refractive index of a mineral. Once again briefly explained: Isotropic gemstones (e.g. diamonds, garnets, spinels) have simple light refraction (only one light refraction index). Anisotropic gemstones (e.g. rubies, sapphires, alexandrites) have double refraction (two refraction indices). When measuring the refractive index on an anisotropic gemstone, one can determine the presence of two refractive indices. If you turn the gemstone on your table, these two indices can fluctuate. Double refraction is the presence of two refractive indices and the maximum deviation between these two. Very few gemstones are easy to break, the only known gemstones with this property are the diamond, spinel and garnet colored gemstones.

The table below lists the refractive index (first numerical value) for various gemstones and gemstones in alphabetical order. If there is birefringence, this is indicated with a value (second numerical value):

Agate 1.53-1.54 Yes up to 0.004
Agate Geode 1.53-1.54 Yes up to 0.004
Alexandrite 1.746-1.763 Yes 0.004-0.010
Almandine Garnet 1.77-1.82 None
Amazonite 1.522-1.53 ​​Yes 0.008
Amethyst 1.544-1.553 Yes 0.009
Ametrine 1.544-1.553 Yes 0.009
Ammolite 1.52-1.68 Yes 0.155
Andalusite 1.627-1.649 Yes 0.007-0.013
Apatite 1.628-1.649 yes 0.002-0.006
Aquamarine 1.564-1.596 Yes 0.004-0.005
Aventurine 1.544-1.553 Yes 0.009
Axinite 1.656-1.704 yes 0.010-0.012
Azotic Topas 1.609-1.643 Yes 0.008-0.016
Azurite 1.72-1.848 yes 0.108-0.110
Amber 1.539-1.545 None
Beryl 1.562-1.602 Yes 0.004-0.010
Boulder Opal 1.37-1.52 None
Calcite (calcite) 1.486-1.658 Yes 0.172
Chalcedony 1.53-1.54 Yes up to 0.004
Charoite 1.55-1.561 Yes 0.004-0.009
Chromium Diopside 1.664-1.73 Yes 0.024-0.031
Chrome tourmaline 1.614-1.666 yes 0.014-, 032
Chrysoberyl 1.746-1.763 Yes 0.007-0.011
Chrysoberyl Cat's Eye 1.746-1.763 Yes 0.004-0.010
Chrysocolla 1.469-1.57 Yes 0.023-0.040
Chrysoprase 1.53-1.54 Yes 0.004-0.009
Citrine 1.544-1.553 Yes 0.009
Danburite 1.63-1.636 Yes 0.006-0.008
Demantoid Garnet 1.88-1.94 None
Dendritic Agate 1.53-1.54 Yes up to 0.004
Diamond 2.417-2.419 None
Dumortierite Quartz 1.678-1.689 Yes 0.015-0.037
Strawberry Quartz 1.544-1.553 Yes 0.009
Peanut wood 1.54 None
Color change diaspore 1.702-1.75 yes 0.048
Color change garnet 1.73-1.756 None
Color change sapphire 1.762-1.788 Yes 0.008
Fire agate 1.53-1.54 Yes up to 0.004
Fire Opal 1.37-1.52 None
Fluorite (fluorspar) 1.434 None
Fossil coral 1.53-1.54 Yes up to 0.004
Gaspeit 1.61-1.81 Yes 0.22
Goshenite 1.562-1.602 yes 0.004-0.010
Grossular Garnet 1.734-1.759 None
Hackmanit 1.48 None
Hematite 2.94-3.22 Yes 0.287
Hambergite 1.553-1.628 Yes 0.0072
Heliotrope 1.53-1.54 Yes up to 0.004
Hemimorphite 1.614-1.636 Yes 0.022
Hessonite Garnet 1.73-1.75 None
Hiddenite 1.66-1.681 Yes 0.014-0.016
Howlite 1.586-1.605 yes 0.019
Idocras 1.7-1.723 Yes 0.002-0.012
Imperial Topaz 1.609-1.643 Yes 0.008-0.016
Iolite 1.542-1.578 Yes 0.008-0.012
Jasper 1.54 None
Carnelian 1.53-1.54 Yes up to 0.004
Cassiterite 1.997-2.098 Yes 0.096-0.098
Cat's Eye Scapolite 1.54-1.579 Yes 0.006-0.037
Cat's Eye Tourmaline 1.614-1.666 Yes 0.014-0.032
Cat's Eye Apatite 1.628-1.649 Yes 0.002-0.006
Cat's Eye Aquamarine 1.564-1.596 Yes 0.004-0.005
Cat's Eye Diaspore 1.702-1.75 Yes 0.048
Klinohumit 1.629-1.674 Yes 0.029-, 045
Coral 1.486-1.658 Yes 0.160-0.172
Kunzite 1.66-1.681 Yes 0.014-0.016
Kyanite 1.71-1.734 yes 0.015-0.033
Labradorite 1.559-1.57 Yes 0.008-, 010
Lapis Lazuli 1.5 None
Larimar 1.595-1.645 Yes 0.038
Lepidolite 1.525-1.586 Yes 0.0290-0.0380
Malachite 1.655-1.909 Yes 0.254
Mali Garnet 1.734-1.759 None
Maw-Sit-Sit 1.52-1.74 Yes 0.015-0.020
Melanite 1.88-1.94 None
Moldavite 1.48-1.54 None
Moonstone 1.518-1.526 Yes 0.008
Morganite 1.562-1.602 Yes 0.004-0.010
Mossopal 1.37-1.52 None
Mystic Quartz 1.544-1.553 Yes 0.009
Mystic Topaz 1.609-1.643 Yes 0.008-0.016
Natural jade (jadeite) 1.6-1.627 yes 0.027
Nephrite Jade 1.6-1.627 Yes 0.027
Obsidian 1.45-1.55 None
Onyx 1.544-1.553 Yes up to 0.004
Opal 1.37-1.52 None
Opal Doublette 1.37-1.52 None
Orthoclase 1.518-1.53 ​​Yes 0.008
Paraiba tourmaline 1.614-1.666 yes 0.014-0.032
Peridot 1.65 to 1.703 Yes 0.036-0.038
Pearl 1.52-1.69 yes 0.156
Pietersite 1.544-1.553 Yes 0.009
Prehnite 1.611-1.669 Yes 0.0021-0.039
Pyrope Garnet 1.72-1.756 None
Quartz 1.544-1.553 Yes 0.009
Quartz Cat's Eye 1.534-1.54 None
Smoky Quartz 1.544-1.553 Yes 0.009
Rainbow moonstone 1.518-1.526 yes 0.008
Rhodochrosite 1.6-1.82 Yes 0.208-0.220
Rhodolite Garnet 1.72-1.76 None
Rhodonite 1.716-1.752 Yes 0.010-0.014
Rose quartz 1.544-1.553 Yes 0.009
Rubellite Tourmaline 1.614-1.666 Yes 0.014-, 032
Ruby 1.762-1.778 Yes 0.008
Ruby Zoisite 1.691-1.7 Yes 0.009
Rutile Topaz 1.609-1.643 Yes 0.008-0.016
Rutile quartz 1.544-1.553 yes 0.009
Sapphire 1.762-1.778 Yes 0.008
Snowflakes Obsidian 1.45-1.55 None
Seraphinite 1.576-1.599 Yes 0.005-0.011
Serpentine 1.56-1.571 yes 0.008-0.014
Sillimanit cat's eye 1.655-1.684 yes 0.014-0.021
Scapolite 1.54-1.579 Yes 0.006-0.037
Emerald 1.565-1.602 yes 0.006
Smithsonite 1.621-1.849 Yes 0.228
Sodalite 1.48 None
Sun stone 1.525-1.548 yes 0.010
Spessartite Garnet 1.79-1.82 None
Sphalerite 2,368-2,371 None
Spinel 1.712-1.762 None
Spodumene 1.66-1.681 Yes 0.014-0.016
Stern Diopside 1.664-1.73 Yes 0.024-0.031
Star sapphire 1.762-1.778 yes 0.008
Star Garnet 1.72-1.756 None
Star moonstone 1.518-1.526 yes 0.008
Star rose quartz 1.53-1.54 Yes 0.009
Star ruby ​​1.762-1.778 yes 0.008
Star sun stone 1.525-1.548 yes 0.010
Sugilite 1.607-1.611 Yes 0.001-0.004
Tanzanite 1.691-1.7 Yes 0.009
Tashmarin Diopside 1.664-1.73 Yes 0.024-0.031
Tiger eye 1.534-1.54 None
Tiger Eye Matrix 1.534-1.54 None
Titanite 1.843-2.11 Yes 0.100-0.192
Topaz 1.609-1.643 Yes 0.008-0.016
Tsavorite (Tsavolite) Garnet 1.734-1.759 None
Turquoise 1.61-1.65 yes 0.040
Tourmaline 1.614-1.666 Yes 0.014-0.032
Variscit 1.563-1.594 Yes 0.031
Verdit 1.552-1.576 None
Zircon 1.81 to 2.024 Yes 0.002-0.059