What does hardness mean for gemstones and jewellery?
By Jared James · Last updated 21 May 2026
Definition
Hardness, in the context of gemstones and jewellery, refers to how well a material resists being scratched, and it is rated on the Mohs scale from 1, which is the softest, to 10, which is diamond. A stone with a higher number can scratch anything below it, so a sapphire at 9 will scratch glass and most metals with ease. Hardness matters when choosing pieces for everyday wear, since softer stones like opal and pearl pick up surface marks quickly, while harder ones like ruby and diamond hold their polish for years.
Frequently asked questions
- What is the Mohs hardness scale?
- The Mohs scale is a simple 1-to-10 system devised by Friedrich Mohs in 1812 to rank how resistant minerals are to scratching. Diamond sits at 10, and each mineral on the scale can scratch everything below it. Gemologists use it as a quick guide to how durable a stone will be in jewellery.
- Which gemstones are hard enough for everyday rings?
- Stones rated 7 or above on the Mohs scale are generally considered suitable for everyday wear in rings, because they resist the fine abrasive dust in ordinary air, which rates around 7. Diamonds, sapphires, rubies and moissanite all sit at 9 or above, while softer stones like opal and turquoise are better suited to earrings or occasional-wear pieces.
- Is hardness the same as toughness in gemstones?
- They are related but different. Hardness is resistance to scratching, while toughness is resistance to breaking or chipping. A diamond is the hardest known natural material but it can still chip along its cleavage planes if struck sharply, while jade scores lower on hardness but is exceptionally tough and resistant to fracture.
Designing a ring
Talk through hardness with us
Tell us what you have in mind, even if it is only a budget and a piece of jewellery type, and we will help you weigh up the options. We reply to every enquiry, usually within one business day.
Contact the studio