MOHS HARDNESS SCALE

Mohs hardness scale is one of the more popular techniques when it comes to evaluating physical characteristics of a gemstone or any other material for that matter. The scale is named after Friedrich Mohs, a German geologist/mineralogist, who developed it in 1812 after more than a decade of intense gemstone studying. 

As its name implies, the scale measures hardness of a gemstone or any other material where hardness is defined as material's ability to inflict scratches on another material. In other words, if gemstone A has the ability to scratch gemstone B, then gemstone A must be harder than gemstone B. Being softer by this logic, gemstone B then can't scratch gemstone A. The scale is from 1 to 10 with higher number in the scale indicating increasing hardness.

Here is the complete scale:

Many scholars consider the scale too simplistic and somewhat misleading as it does not measure the difference between various hardness levels well. For example, diamond is not twice as hard as apatite. It's actually much harder if one were to use an alternate scale that is more precise. 

However, the scale is still very useful as it's easy to remember. It also allows one to effortlessly approximate the hardness level of a material whose hardness is not exactly known at the time when it's measured. 

For example, let's suppose that a mineralogist discovers a gemstone never seen before. If this newly discovered gemstone scratches apatite but it does not scratch quartz, he will know that its hardness is between 5 and 7 and can now be grouped with other materials in such hardness range. That's a good start!

One area where the Mohs hardness scale is very relevant is gemstone jewelry and its maintenance. As indicated in our guide to jewelry care, a consumer can theoretically determine what kind of jewelry design is compatible with his or her lifestyle using the knowledge of the Mohs hardness scale. 

If one's lifestyle is very active (i.e. plenty of exercise), he or she should shy away from the jewelry that's crafted out of less harder materials such as pearls (hardness of 2.5 - 4) and fluorite (hardness of 4) as even the smallest physical impact could have a detrimental impact on their appearance. In fact, any material with a hardness of less than 7 is likely to get scratched sooner or later. 

On the other hand, harder materials such as diamond (hardness of 10) and ruby (hardness of 9) should be more compatible with such an active lifestyle as they should be able to resist scratches and dents much better. 

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