Mohs Scale of Hardness for Metals and Gemstones

"Hardness" is the resistance of a material to being scratched. The Mohs Hardness Scale was developed by German geologist and mineralogist Friedrich Mohs in 1812, and has also been used ever since by jewelers as a guide for working with metals and gemstones. Basically, we take extra care not to scratch or break any gemstone that has a Mohs hardness of 6 and below. This means that "soft" gemstones cannot be placed in a tumbler containing steel pins or shots for polishing. If we really need to use a tumbler, we usually polish the jewelry first before stone setting. These charts show the gemstones that our students often work with.