The Mohs scale of mineral hardness

The Mohs scale of mineral hardness helps to categorize gemstones in order of how hard, or scratch-resistant they are. The scale was created in 1812 by German mineralogist and geologist, Friedrich Mohs and is used to help identify gemstones to this day.

To identify a gemstone, scratch testes are performed, where you use a mineral to physically scratch another mineral to determine its hardness. If a mineral scratches another, we know it is harder than the other mineral.

The scale is not relative, for instance, Corundum (9) is twice as hard as Topaz (8), but diamond (10) is four times as hard as Corundum.

1-Talc

2-Gypsum

3-Calcite

4-Fluorite

5-Apatite

6-Orthoclase Feldspar

7-Quartz

8-Topaz

9-Corundum (Sapphire and Ruby)

10-Diamond

The softest gemstone on the scale that can be realistically used for jewellery is Calcite, though this stone is so soft it will wear down and break easily if worn in rings. Gypsum and Talc are both too soft to wear in jewellery, though do lend themselves to decorative carvings.

The fact that diamonds are so hard is one of the main reasons they are so good for engagement rings, you can wear a diamond every day for your whole life and it won’t scratch. Diamonds can chip if they get a knock in the wrong place, but this is very unlikely.

Rubys and Sapphires which are both Corundum, are also OK to be worn as engagement rings, however, they will show signs of wear over time and will need to be re-cut and polished. This will bring the stone back to its best however it will mean the stone will get smaller and lose some value.

All other gemstones are not advised to be worn in rings that are worn continuously.

Amethyst, a variety of Quartz, measure 7 on the scale

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