What is the Mohs scale?

You've probably noticed it on our technical data sheets: when we talk about stone hardness, we're talking about the Mohs scale. But what exactly is the Mohs scale?

The Mohs scale is a classification system used to measure the hardness of minerals, particularly precious and gemstones (the current name for semi-precious stones). It was devised and developed by German mineralogist Frederich Mohs in 1812. It ranges from 1 for the softest stones (such as talc) to 10 for the hardest (diamond).
How to use the Mohs scale? The hardness of stones is established by comparison with ten reference gemstones: talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum and diamond.

Knowledge of this hardness scale is essential when designing jewelry. This tool will enable you to choose a fine stone according to its intended use. For example, a quartz stone with a hardness of 7 is perfect for creating a ring that will be worn every day. But a calcite stone with a hardness of 3 will be more suitable for a piece of jewelry worn occasionally.

Find out more about stone hardness in our gemstone primer or in our gemstone guide.

Stone classification according to Mohs' scale

There are other complementary tools that measure the hardness of materials, particularly natural stones, such as the Knoop scale, the Brinell scale or the Rockwell scale. But the Mohs scale remains the most widely used method.