INTRINSIC CHARACTERISTICS

Mohs Scale of Hardness

Gams vary widely in hardness. The most commonly used measuremrnt of hardness is a system developed by a nineteenth-century viennese mineralogist, Friedrich Mohs, and called the Mohs scale after him. The scale is based on a range of 1 through 10, using a : mineral to typify or stand for all other minerals of the same "s. The number 1 indicates the softest mineral and 10.

The purpose of the scale is to use hardness as a test for identifying minerals. If one stone scratches another, the first is the harder -d must be a mineral above the other mineral on the scale. If neither stone is scratched, they are of equal hardness and in the on the scale.

Thus, each mineral on the scale will all minerals lower than it on the scale; that same mineral scratched by all minerals higher than it on the scale; and it will not scratched by another mineral of equal hardness because minerals have the same number or degree of hardness on e An even more precise definition for hardness of gems, therefore, is scratchability-how easy or difficult it is for a gem to be scratched.

The Mobs scale may seem esoteric since few people want to identify stones. In addition, you would not want to experiment with your jewelry and run the risk of ruining the stones. Still, the Mohs scale is pertinent to understanding gems and may sometimes be used in talking or writing about gems-and it does have practical aspects in its interpretation.

One point to keep in mind in looking at the list below is that the minerals listed are test or sample minerals. They stand for all minerals of that hardness. Another point is that the disparity between the numbers is not equal. Diamonds are so much harder than other minerals that the disparity between diamonds and the next hardest mineral is far greater than between that mineral (corundum) and the lowest one on the scale.