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One of the most common questions we get from customers is “what is the hardness of this crystal or mineral?” This article will explains the Mohs Scale of Hardness—how it works, how to test stones,
and give you a detailed gemstone hardness reference table for collectors.
The Mohs scale of mineral hardness is a qualitative scale from 1 (softest) to 10 (hardest) that measures a mineral’s resistance to scratching. Introduced in 1812 by German mineralogist Friedrich Mohs,it remains one of the simplest and most effective ways to identify minerals in the field.
To determine a specimen’s hardness, try to scratch it with a mineral from the Mohs scale. If the specimen is scratched, it’s softer than that mineral. If it scratches the test mineral, it’s harder. Continue testing up or down the scale until you find its hardness range.
Prefer not to scratch your specimen’s, no worries you can use this reference section as a guide. This section does not contain all minerals but the most common. The information below is referenced from the International Gem Society.
Diamond – 10
Synth. Moissanite – 9½
Ruby – 9
Sapphire – 9
Alexandrite – 8½
Chrysoberyl – 8½
Spinel – 8
Topaz – 8
Aquamarine – 7½–8
Emerald – 7½–8
Tourmaline – 7–7½
Amethyst – 7
Quartz – 7
Garnet – 6½–7½
Zircon – 6½–7½
Jadeite – 6½–7
Peridot – 6½–7
Pyrite – 6–6½
Amazonite – 6–6½
Nephrite – 6–6½
Turquoise – 5–6
Opal – 5½–6½
Lapis Lazuli – 5–6
Apatite – 5
Dioptase – 5
Fluorite – 4
Rhodochrosite – 4
Calcite – 3
Malachite – 3½–4
Azurite – 3½–4
Howlite – 3–3½
Pearl – 2½–4½
Amber – 2–2½
Gypsum – 2
Chrysocolla – 2–4 Talc – 1
The Mohs Hardness Scale is a simple yet powerful tool used by gem collectors, jewelers, and mineral enthusiasts to identify stones by their resistance to scratching. First introduced in 1812 by Friedrich Mohs, the scale ranks minerals from 1 (softest, talc) to 10 (hardest, diamond). By performing a scratch test or consulting a gemstone hardness chart, collectors can quickly compare stones such as quartz, topaz, or sapphire to determine durability and care needs. While hardness is a key identifying factor, it should always be considered alongside other properties like luster, streak, and crystal form for accurate mineral identification. If you enjoyed this article and would like to read more check out our other mineral articles.
At Grounded Lifestyles, our love for crystals began in the peaceful flow of Reiki and energy healing sessions — where we saw how natural stones could amplify intentions, restore balance, and bring comfort. But the more time we spent with these treasures, the more curious we became about their origins. That curiosity led us into the fascinating world of geology and mineral specimen collecting. We fell in love not just with the energy of crystals, but with the science and artistry of their creation — the intricate crystal structures, the vibrant mineral hues, and the wonder of holding a piece of Earth’s history in our hands.
