The word "hardness" is often mentioned in literary circles. For example, the hardness of diamond is 10, the hardness of lapis lazuli is 5~6, and the hardness of amber is 2~2.5. So, what does this hardness mean? Does the smaller the number mean that this thing is softer? In fact, the "hardness" in the literary circle is not a soft or hard concept in our life, but refers to the scratch and wear resistance of jewelry and jade, so it is also called Mohs hardness.

Mohs hardness is a standard to express mineral hardness, which was first put forward by German mineralogist Frederick Moss. As mentioned above, the hardness in jewelry and jade is a test of its wear resistance, so Mohs hardness is also a measure of the scratch depth on the surface of the tested mineral.

Generally speaking, Mohs hardness is divided into ten grades, from low to high, namely talc, gypsum, calcite, fluorite, apatite, orthoclase, timely, topaz, corundum and diamond. These ten kinds will be used as reference when testing other jewels and jade. If a mineral can scratch calcite but not fluorite, its Mohs hardness will be 3~4.

So, having said that, what is the specific use of Mohs hardness in the literary circle?

First of all, Mohs hardness is one of the testing methods to judge the texture of jewelry and jade. For example, porcelain pine is considered to be the hardest turquoise, and its Mohs hardness is basically between 5.5 and 6. When the modal hardness of turquoise is below 4.5, then its texture is not hard enough, which is what we call puffiness, and its playing value is obvious.

Secondly, after a long period of exploration and inspection, most jewels and jade have Mohs hardness range. Therefore, in the process of identifying jewelry and jade, Mohs hardness can also be used to judge some jewelry and jade with similar appearance, which has become one of the methods to distinguish authenticity.