Beautiful jewellery, brilliant design. 

How the hardness of gemstones matters

Posted on July 31, 2015 by Shayna Gavin, Jewellery Designer, Sky with Diamonds

We specialise in helping to bring your jewellery ideas to life

Call it custom design, made it order, or bespoke jewellery, we love to turn sketches into beautiful pieces of jewellery. 

One of the biggest considerations is the gemstones you use. 

Rings that will be worn most days, for many years, need to be carefully designed. 

  • for their beauty
  • sentimental value
  • and longevity!

This is especially important for engagement rings

The stones used in jewellery need to be durable enough to withstand daily wear. 

Gemmologists use the Moh's scale of hardness. In this context, we are talking about hardness meaning ability to resist scratching.

For example: 

1  Talc can be scratched by a fingernail
2 Gypsum can be scratched by a fingernail
3 Calcite can be scratched by a copper coin
4 Fluorite can be scratched by a knife
5 Apatite can be scratched by a knife
6 Felspar can be scratched by a steel file
7 Quartz will scratch window glass
8 Topaz

Rubies, sapphires

10 Diamond


Those higher up the scale will scratch those below.

For rings intended to be worn most days, like an engagement ring, we would like the stones to have a hardness of 7 or greater.

If you love a gemstone which is lower on the Moh's scale, it can be worn in a pendant, or as earrings, where it will be subjected to much fewer wear and tear forces.

How does this relate to wearability?

Hardness is only one factor related to wearability. Other things to consider include: 

  • heat sensitivity eg. opals
  • how brittle a gemstone is, and how easily they chip eg. apatite
  • chemical sensitivity eg. turquoise and pearls, which are soft and porous
  • the setting you will use on a ring eg. a high set solitaire stone will be subjected to far more knocks in its life, even if worn only on dress occasions. This is best reserved for very durable gemstones, like diamonds

Further resources: 

This is a great resources with more information about the Moh's scale, and how it relates to hardness and wearability

The International Gem Society's website has many gemstones listed where you can see all information about them, including their hardness. 


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