What is the Mohs Hardness Scale and when is it used?

The Mohs scale of mineral hardness is a scale that informs us about the resistance to scratching of various minerals and metals. This consequently means that this scale is an indicator of how sturdy and resistant to wear each material is. This measurement system was created in 1812 by German geologist and mineralogist Friedrich Mohs.

This method of comparison stems from antiquity where people used to compare hardness by observing which mineral can scratch others.
This was even recorded by Pliny the Elder and Theophrastus in Ancient Greek and Roman Times.

Why is the Mohs Hardness Scale still relevant today?

Measuring mineral hardness is of paramount importance when you want to know how to handle your Jewellery or materials in general.

For example, pearls have a hardness of 2.5-4.5/10 on Mohs hardness scale. This means that the material pearls are made of (calcium carbonate) is quite brittle and should be handled with care! On the other side, Diamonds have a hardness of 10/10 which makes them the hardest material on earth.

Mohs hardness can also be useful in milling. It discerns which kind of mill will best reduce a given product with known hardness.4

The hardness scale is also used in the technology sector for testing the hardness of screen glasses of OLED and LCD panels.  Most modern displays for phones and tablets have a hardness of 6+/10 in Mohs hardness scale.

How Professionals Test Hardness with Mohs scale

They first find a smooth surface that is in perfect shape and ideal for testing that has an unknown hardness. Then with one hand, they take specimens with known hardness and press them down on the surface that is being tested.

When they reach a material that can put a dent on the surface with unknown hardness they know how hard the surface is because of what it could withstand prior to the dent.

If you can scratch the surface with a material that features a hardness of 7/10 then the surface also has that hardness. After this, the test is conducted once again to ensure correct results!

What is the hardness of my gemstone jewellery and other minerals?

Gemstone Jewels and Metals from 1 to 10

2.75/10 18K Gold 

2.5-4.5/10 Pearl

4-4.5/10 Platinum

7/10 Amethyst

7/10 Agate

7/10 Citrine

6.5-7.5/1o Garnet

7-7.5 Tourmaline

7.5-8/10 Emerald

8/10 Topaz

8.5/10 Alexandrite

8.5/10 Cubic Zirconia

9/10 Sapphire

9/10 Ruby

10/10 Diamond

Minerals from 1 to 10

From 1 to 10  Mohs hardness scale of mineral hardness has a set example of minerals to depict each individual value.

1/10 Talc 

2/10 Gypsum

3/10 Calcite

4/10 Fluorite

5/10 Apatite

6/10 Orthoclase feldspar 

7/10 Quartz

8/10 Topaz

9/10 Corundum

10/10 Diamond



Hardness is a very important characteristic of gemstones that help you identify how durable your jewellery is. If your Jewellery is relatively brittle and easy to damage (which translates to a low rank on the hardness scale) you should take really good care of it and be extra careful when wearing it.