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![Infographic on the Mohs Mineral Hardness Scale. The graphic shows the scale, which runs from 0-10, and also highlights a number of minerals with their point on the scale. Key reference minerals for each point on the scale are also shown: 1 = talc, 2 = gypsum, 3 = calcite, 4 = fluorite, 5 = apatite, 6 = feldspar, 7 = quartz, 8 = topaz, 9 = corundum, 10 = diamond.](https://i0.wp.com/www.compoundchem.com/wp-content/uploads/2022/11/Mohs-Hardness-Scale.png?resize=370%2C208&ssl=1)
Diamond is commonly known to be the hardest material, but how do other minerals compare with each other? That’s the question the Mohs hardness scale, introduced by Friedrich Mohs in 1812, aims to answer. This graphic looks at his scale and where different minerals and other substances appear on it.
![The Chemistry of Gemstone Colours 2016](https://i0.wp.com/www.compoundchem.com/wp-content/uploads/2014/06/The-Chemistry-of-Gemstone-Colours-2016.png?resize=370%2C208&ssl=1)
There are a wide range of gemstones used in jewellery, with each having its own characteristic colour – or, in some cases, a range of colours. The origin of these colours has a chemical basis, and the precise colour can vary depending on the chemical composition of the gemstone. Interestingly, many minerals are actually colourless in their pure form, and it is the inclusion of impurities in their structure which leads to their colouration.