What is the Mohs scale?

Created in 1812 by mineralogist Friedrich Mohs, this scale ranks minerals according to their ability to scratch another material. It ranges from 1 (talc, extremely brittle) to 10 (diamond, the hardest stone known). In practical terms, a stone graded 7 will be able to scratch a stone graded 6, but will itself be scratched by a higher graded stone.

The impact of hardness on jewellery

In jewellery, the hardness of a stone plays a crucial role in its durability. For example, a diamond (10 on the scale) is ideal for an engagement ring, as it resists scratches and everyday knocks. On the other hand, a stone like opal (around 5-6) requires more attention and care to avoid scratches.

Here are some examples of stones commonly used in jewellery and their hardness on the Mohs scale:

• Diamond 10 (very resistant, ideal for everyday wear)

• Sapphire and ruby 9 (excellent resistance, perfect for rings and bracelets)

• Topaz 8 (solid but may chip on impact)

• Quartz : 7 (fairly resistant but sensitive to shocks)

• Opal and turquoise : 5-6 (fragile, handle with care)

How do you choose?

If you are looking for a piece of jewellery to wear every day, choose stones with a hardness of at least 7 to avoid scratches. For pieces intended for special occasions, softer stones may be suitable, provided they are handled with care and stored correctly.