Which scale is used to express the hardness of a gemstone?

The Mohs scale is specifically designed to measure the hardness of various minerals, including gemstones. Developed by Friedrich Mohs in 1812, this scale ranks minerals based on their ability to scratch one another, providing a straightforward method for determining hardness. The scale ranges from 1 to 10, with talc being the softest (1) and diamond being the hardest (10). This ranking helps gemologists assess the durability of gemstones in jewelry applications, as harder stones are generally more resistant to scratching and damage.

In contrast, the other options refer to different concepts. The beauty scale is not a standardized measurement in gemology and does not pertain to hardness. The durability scale relates to various factors that contribute to a gemstone's overall resilience, including hardness but also toughness and stability. The tensile scale measures the ability of a material to withstand being pulled apart, which is not directly related to the identification of gemstone hardness. Thus, the Mohs scale is the recognized standard for expressing the hardness of gemstones.