Gemstone Hardness: The Definitive Guide

This illustrated chart shows hardness ratings for 155 natural gemstone varieties. It is the most complete and accurate hardness scale for gemstones available online, and includes many rare varieties.

Click on a gem link to see examples or find more information.

Natural Diamond Diamond 10
Natural Ruby Ruby 9
Star Ruby Star Ruby 9
Sapphire Sapphire 9
Star Sapphire Star Sapphire 9
Color Change Alexandrite Alexandrite 8.5
Alexandite Cat's Eye Alexandrite Cat's Eye 8.5
Chrysoberyl Chrysoberyl 8.5
Chrysoberyl Cat's Eye Chrysoberyl Cat's Eye 8.5
Vanadium Chrysoberyl Vanadium Chrysoberyl 8.5
Taaffeite Taaffeite 8-8.5
Spinel Spinel 8
Topaz Topaz 8
Imperial Topaz Imperial Topaz  8
Pezzotaite Pezzotaite 8
Emerald Emerald 7.5-8
Enstatite Enstatite 7.5-8
Aquamarine Aquamarine 7.5-8
Morganite Morganite 7.5-8
Goshenite Beryl Goshenite Beryl 7.5-8
Golden Beryl Golden Beryl 7.5-8
Painite Painite 7.5-8
Phenakite Phenakite 7.5-8
Red Beryl Red Beryl (Bixbite) 7.5-8
Andalusite Andalusite 7.5
Euclase Euclase 7.5
Grandidierite Grandidierite 7.5
Hambergite Hambergite 7.5
Dumortierite Dumortierite 7-8.5
Almandine Garnet Almandine Garnet 7-7.5
Danburite Danburite 7-7.5
Iolite Iolite 7-7.5
Pyrope Garnet Pyrope Garnet 7-7.5
Spessartite Garnet Spessartite Garnet 7-7.5
Rhodolite Garnet Rhodolite Garnet 7-7.5
Color Change Garnet Color-Change Garnet 7-7.5
Chrome Tourmaline Chrome Tourmaline 7-7.5
Malaia Garnet Malaia Garnet 7-7.5
Paraiba Tourmaline Paraiba Tourmaline 7-7.5
Rubellite Tourmaline Rubellite Tourmaline 7-7.5
Tourmaline Tourmaline 7-7.5
Uvarovite Garnet Uvarovite Garnet 7-7.5
Amethyst Amethyst 7
Aventurine Aventurine 7
Ametrine Ametrine 7
Citrine Citrine 7
Gem Silica Gem Silica 7
Kornerupine Kornerupine 7
Rock Crystal Rock Crystal 7
Rose Quartz Rose Quartz 7
Smoky Quartz Smoky Quartz 7
Jeremejevite Jeremejevite 6.5-7.5
Sillimanite Sillimanite 6.5-7.5
Zircon Zircon 6.5-7.5
Agate Agate 6.5-7
Axinite Axinite 6.5-7
Bloodstone Bloodstone 6.5-7
Carnelian Carnelian 6.5-7
Chalcedony Chalcedony 6.5-7
Chrome Chalcedony Chrome Chalcedony 6.5-7
Chrysoprase Chrysopase 6.5-7
Demantoid Garnet Demantoid Garnet 6.5-7
Diaspore Diaspore 6.5-7
Grossular Garnet Grossular Garnet 6.5-7
Hessonite Garnet Hessonite Garnet 6.5-7
Hiddenite Hiddenite 6.5-7
Jadeite Jade Jadeite Jade 6.5-7
Jasper Jasper 6.5-7
Mali Garnet Mali Garnet 6.5-7
Kunzite Kunzite 6.5-7
Leuco Garnet Leuco Garnet 6.5-7
Onyx Onyx 6.5-7
Peridot Peridot 6.5-7
Serendibite Serendibite 6.5-7
Sinhalite Sinhalite 6.5-7
Spodumene Spodumene 6.5-7
Tanzanite Tanzanite 6.5-7
Tsavorite Garnet Tsavorite Garnet 6.5-7
Idocrase (Vesuvianite) Idocrase (Vesuvianite) 6.5
Cassiterite Cassiterite 6-7
Epidote Epidote 6-7
Maw-Sit-Sit Maw-Sit-Sit 6-7
Unakite Unakite 6-7
Amazonite Amazonite 6-6.5
Andesine Andesine 6-6.5
Oligoclase Oligoclase 6-6.5
Benitoite Benitoite 6-6.5
Labradorite Labradorite 6-6.5
Moonstone Moonstone 6-6.5
Nephrite Jade Nephrite Jade 6-6.5
Orthoclase Orthoclase 6-6.5
Petalite Petalite 6-6.5
Prehnite Prehnite 6-6.5
Scheelite Scheelite 6-6.5
Sugilite Sugilite 6-6.5 
Sunstone Sunstone 6-6.5
Zoisite Zoisite 6-6.5
Amblygonite Amblygonite 6
Clinohumite Clinohumite 6
Hematite Hematite 5.5-6.5
Mexican Fire Opal Mexican Fire Opal 5.5-6.5
Opal Opal 5.5-6.5
Rhodonite Rhodonite 5.5-6.5
Actinolite Actinolite 5.5-6
Azurite Azurite 5.5-6
Hackmanite Hackmanite 5.5-6
Hauyne Hauyne 5.5-6
Scapolite Scapolite 5.5-6
Sodalite Sodalite 5.5-6
Moldavite Moldavite 5.5
Diopside Diopside 5-6
Chrome Diopside Chrome Diopside 5-6
Lapis Lazuli Lapis Lazuli 5-6
Poudretteite Poudretteite 5-6
Turquoise Turquoise 5-6
Brazilianite Brazilianite 5.5
Datolite Datolite 5-5.5
Eudialyte Eudialyte 5-5.5
Obsidian Obsidian 5-5.5
Sphene (Titanite) Sphene (Titanite) 5-5.5
Apatite Apatite 5
Cat's Eye Apatite Cat's Eye Apatite 5
Dioptase Dioptase 5
Hemimorphite Hemimorphite 5
Smithsonite Smithsonite 5
Charoite Charoite 4.5-5
Gaspeite Gaspeite 4.5-5
Larimar Larimar 4.5-5
Kyanite Kyanite 4-7
Bastnasite Bastnasite 4-5
Carletonite Carletonite 4-4.5
Ammolite Ammolite (Korite) 4
Fluorite Fluorite 4
Rhodochrosite Rhodochrosite 4
Williamsite Williamsite 4
Aragonite Aragonite 3.5-4
Azurite Azurite 3.5-4
Cuprite Cuprite 3.5-4
Malachite Malachite 3.5-4
Sphalerite Sphalerite 3.5-4
Coral Coral 3-4
Barite Barite 3-3.5
Celestine Celestine 3-3.5
Cerussite Cerussite 3-3.5
Howlite Howlite 3-3.5
Calcite Calcite  3
Cobaltocalcite Cobaltocalcite 3
Pearl Pearl  2.5-4.5
Jet Jet 2.5-4
Lepidolite Lepidolite 2.5-3
Chrysocolla Chrysocolla 2-4
Amber Amber  2-2.5
Cinnabar Cinnabar 2-2.5
Ulexite Ulexite  2-2.5

In gemology, gem hardness is measured on a scale known as the Mohs scale, which assigns minerals a value between 1 (softest) and 10 (hardest). This scale was devised by a German mineralogist, Frederick Mohs, in 1822. It defines hardness in terms of scratch resistance, where a harder mineral will scratch a softer one, but not vice versa. 

Gems with a hardness rating of 1-2 are considered soft, while those in the range of 3-5 are medium hard. Gems over 6 are considered hard and thus suitable for jewelry.

The polish of gems with a Mohs hardness of less than 7 can be damaged by common dust, which contains tiny particles of quartz (hardness 7). Thus softer stones need to be worn and stored carefully, and repolished from time to time to maintain their luster.

See also:

Gemstone Refractive Index Chart

Gemstone Density Chart

 

 
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