Mohs Scale Hardness Pencils - Set of 5

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This set of 5 hardness pencils covers the range of Moh's Scales from 5 through to 9.

Hardness pencils are pencils with a tip made of one of the minerals on Mohs scale. These pencils are used to try and scratch a stone and observe if the pencils can scratch the gem.

Since this is a destructive method (it leaves a scratch), this test is mostly used on pieces of rough or on a inconspicuous place on the gemstone.

The gemstone is tested with a pencil of low hardness (starting at 4 or lower) to try to put a tiny scratch on the stone without applying pressure. If no scratch is observed, one repeats this process with a pencil of higher hardness (in this case 5) and so on until one arrives at the pencil that is able to put a tiny scratch on the stone.

For instance, if one could not scratch the mineral with pencil no.7 but it would leave a scratch with pencil no.8, the hardness of the mineral must be between 7 and 8 on Mohs scale.



Brand GemPro
Shipping Weight 0.1100kg
Shipping Width 0.025m
Shipping Height 0.140m
Shipping Length 0.150m
Shipping Cubic 0.000525000m3

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