Mohs Scale of Hardness

Mohs Scale of Hardness

The Mohs Scale of Hardness is a standard system used to measure the scratch resistance of minerals and gemstones. In jewellery, it plays a crucial role in determining a gemstone’s durability and suitability for everyday wear.

At Clarindon Jewellers, we use the Mohs Scale as a guide when selecting gemstones for fine jewellery, helping customers make informed and confident choices.

What Is the Mohs Scale of Hardness?

Developed in 1812 by German mineralogist Friedrich Mohs, the Mohs Scale ranks minerals from 1 (softest) to 10 (hardest) based on their ability to scratch one another.

Rather than measuring absolute hardness, the scale compares relative resistance to scratching, making it a practical reference for gemstones used in jewellery.

Mohs Scale of Hardness Chart

Mohs Rating Mineral Common Jewellery Use
1 Talc Too soft for jewellery
2 Gypsum Not suitable for wear
3 Calcite Decorative pieces only
4 Fluorite Limited jewellery use
5 Apatite Occasional wear
6 Feldspar Moderate durability
7 Quartz Good for everyday wear
8 Topaz Excellent durability
9 Corundum (Ruby & Sapphire) Very durable
10 Diamond Ultimate hardness

Why the Mohs Scale Matters in Jewellery

Understanding gemstone hardness is essential when choosing jewellery, particularly for rings and bracelets that are exposed to frequent wear.

Key considerations include:

  • Everyday wear suitability – harder stones resist scratches better

  • Longevity – higher Mohs ratings help maintain polish and appearance

  • Setting choice – softer gemstones require protective settings

  • Care requirements – softer stones need gentler handling

For example, gemstones rated 7 or higher are generally recommended for daily-wear jewellery.

Mohs Scale & Common Gemstones

Here’s how popular gemstones compare on the Mohs Scale:

  • Diamond – 10

  • Ruby & Sapphire – 9

  • Topaz – 8

  • Quartz (Amethyst, Citrine) – 7

  • Garnet – 6.5–7.5

  • Opal – 5.5–6.5

  • Pearl – 2.5–4.5

This variation explains why some gemstones are better suited to specific jewellery types.

Hardness vs Toughness

It’s important to note that hardness is not the same as toughness.

  • Hardness refers to scratch resistance

  • Toughness refers to resistance to chipping or breaking

Some hard gemstones can still be brittle, which is why expert setting and care are essential.

Choosing the Right Gemstone

When selecting jewellery, consider:

  • How often the piece will be worn

  • The type of jewellery (ring, necklace, earrings)

  • Your lifestyle and daily activities

At Clarindon Jewellers, our specialists guide you toward gemstones that balance beauty, durability, and practicality.

Expert Guidance at Clarindon Jewellers

At Clarindon Jewellers, we combine gemstone expertise with craftsmanship to ensure every piece is both beautiful and durable. Understanding the Mohs Scale allows us to recommend gemstones that suit your lifestyle while maintaining long-term elegance.

Explore our gemstone jewellery collections or contact Clarindon Jewellers for personalised advice.