Gemstone hardness is most often measured on the Mohs scale.

• A. Beaufort scale
• B. Vickers scale
• C. Mohs scale
• D. Richter scale

Answer: (C)

Hardness measurement in gemology relies on a simple, widely used scale that ranks minerals by scratch resistance. The Mohs scale assigns numbers to minerals from soft to hard, based on whether one mineral can scratch another. This makes it practical for gemologists and jewelers because it directly relates to how a gemstone will resist everyday wear and scratching. In practice, a gemstone’s hardness is estimated by testing it against reference minerals on the scale, giving a quick, comparable measure of durability.

Other scales measure things unrelated to gemstone wear: the Beaufort scale gauges wind force, the Vickers scale is a precise macro-microhardness test used for metals and other engineered materials, and the Richter scale measures earthquake magnitude. Since the question focuses on how hard a gemstone is, the Mohs scale is the appropriate and most informative reference.