The Mohs Scale explained

In previous blogs and in our care section, we often refer to the Mohs Scale - but what exactly is it and why should you care?

Well, The Mohs scale is a measure of hardness and scratchability of minerals and gemstones.

It was developed by Frederich Mohs in 1822, who ranked the hardness of ten accessible minerals on a scale of one to ten. One represented the softest, while ten represented the hardest. The results were as follows.

1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. Apatite
6. Feldspar
7. Quartz
8. Topaz
9. Corundum
10. Diamond

This scale is not proportional. For example, a mineral given a hardness of 3, will not be as twice as hard as 6. What the scale measures is comparative hardness. Minerals with higher numbers will scratch all minerals that rank below them on the scale. Thus, a Mohs scale rating is determined by finding the hardest material that a given material can scratch, or the softest material that can scratch the given material.

So diamond has a Mohs rating of 10, as it is the hardest mineral. Rubies have a rating of 9. This is because diamond is the only mineral that can scratch them. They appear close to each other on the Mohs scale, even though in reality diamonds are a massive 4 times harder than rubies.

Here is a look at how popular gemstones we sell rank on the Mohs scale.

Gem	Hardness
Diamond	10
Ruby	9
Sapphire	9
Topaz	9
Emerald	8.5
Aquamarine	8.5
Quartz	7.5 - 8
Amethyst	7 - 7.5
Garnet	7-7.5
Citrine	7
Tourmaline	7
Peridot	7
Onyx	6.5 - 7
Zircon	6.5 - 7
Tanzanite	6.5 - 7
Agate	6.5 - 7
Opal	6 - 6.5
Fire Opal	5.5 - 6.5
Turquoise	5.5 - 6.5
Lapis Lazuli	5 - 6
Coral	4.5 - 5
Pearl	4
Amber	3.5 - 4

Knowing how these gems rank allows you to store them more safely. For example, it would not be a good idea to store pearls with hard stones such as diamonds and rubies.

It can also be a good indicator of how often you should wear your gemstone and when. Soft gemstones with a rating of 6 and under should not be worn in situations where they are likely to be knocked and chipped. Equally, hard stones such as diamonds, rubies and sapphire work well in engagement rings because they are harder and less likely to get damaged from everyday wear.

Ultimately however, if you have any questions about caring for your jewellery, talk to an expert. At Gatwards, our trained and friendly team are ideally placed to help you with any questions you might have about maintaining and looking after your gems.