<b>Introduction of hardness pen<b/><br> The hardness of a gemstone refers to the ability of the gemstone to resist scoring, pressing and grinding of foreign objects.<br> The hardness of a gemstone is an important factor determining the value of the gemstone.<br> When two minerals with different hardnesses scratch each other, they will leave scratches on the surface of the minerals with lower hardness.<br> <b>Physical scratch test<b/><br> This method is based on the comparison between the engraved gemstone minerals and the standard hardness minerals.<br> The hardness difference between two adjacent standard minerals is different.<br> The difference between corundum and diamond is large.<br> The Mohs hardness pen is 5 # apatite, # 6 orthoclase, 7 # quartz, # 8 Topaz # 9 corundum<br> in the Mohs hardness tester set on five heel metal rods respectively.<br> Use the edges and corners of these ore to score the sample to be tested.<br> According to whether there are scratches on the sample to determine the hardness of the sample:<br> If scratches are left, it means that the hardness of the sample is lower than the hardness of the hardness pen.<br> If it cannot be moved, the hardness of the sample is higher than the hardness of the hardness pen.<br>