The Mohs Hardness Scale

The Mohs Hardness Scale

When it comes to buying jewelry, we often focus on the beauty of the gemstones and the design of the piece. However, one important factor that is sometimes overlooked is the hardness of the gemstone. The Mohs Hardness Scale is a valuable tool that helps us understand how durable and resistant a gemstone is to scratches and damage. In this guide, we'll explore the Mohs Hardness Scale, why it's important when shopping for jewelry, and how it can guide your choices to ensure longevity and wearability.

What is the Mohs Hardness Scale?

The Mohs Hardness Scale, developed by German mineralogist Friedrich Mohs in 1812, is a system used to measure the hardness of minerals and gemstones. It ranks minerals from 1 to 10 based on their ability to resist scratching by another material. The higher the number on the scale, the harder the material.

The Scale:

  • 1-2: Very soft - Can be scratched by a fingernail. (Talc, Gypsum)

  • 3: Soft - Can be scratched by a copper coin. (Calcite)

  • 4: Medium - Can be scratched by a steel knife. (Fluorite)

  • 5: Medium-Hard - Can be scratched by a steel file. (Apatite)

  • 6-7: Hard - Can scratch glass. (Orthoclase, Quartz)

  • 8-10: Very Hard - Can scratch a glass window. (Topaz, Corundum, Diamond)

Why is the Mohs Hardness Scale Important for Jewelry?

  1. Durability: The hardness of a gemstone determines how well it will withstand everyday wear and tear. Jewelry pieces with softer gemstones are more prone to scratches and abrasions, which can dull their appearance over time.

  2. Resistance to Damage: Knowing the hardness of a gemstone helps you understand its susceptibility to chips and cracks. A harder gemstone is less likely to chip or break when accidentally bumped or knocked.

  3. Maintaining Appearance: Gemstones that rank high on the Mohs Scale will retain their polish and shine for longer periods. This is especially important for stones like diamonds, sapphires, and rubies that are often worn daily.

  4. Compatibility with Settings: Different settings and styles of jewelry require different gemstone hardness. For example, softer stones may not be suitable for rings that are worn daily, while harder stones are ideal for engagement rings and other frequently worn pieces.

Popular Gemstones and Their Mohs Hardness:

  1. Diamond (10): The hardest gemstone on the Mohs Scale, diamonds are perfect for everyday wear, especially in engagement rings and wedding bands.

  2. Sapphire (9): Sapphires are a durable choice, making them ideal for rings and other frequently worn jewelry.

  3. Ruby (9): Like sapphires, rubies are also a 9 on the Mohs Scale, offering excellent durability.

  4. Emerald (7.5-8): Emeralds are softer compared to diamonds and sapphires, so they require more care, especially in rings.

  5. Amethyst (7): Amethyst is a popular gemstone, but it requires more care due to its medium hardness.

  6. Aquamarine (7.5-8): Aquamarine has good durability but should be protected from hard knocks.

  7. Pearl (2.5-4.5): Pearls are softer and should be handled carefully to avoid scratches.

How to Use the Mohs Hardness Scale When Shopping for Jewelry:

  1. Consider Lifestyle: If the jewelry will be worn daily, choose gemstones with higher hardness levels like diamonds, sapphires, or rubies.

  2. Check Settings: Ensure that the gemstone is securely set, especially if it's a softer stone like emerald or opal.

  3. Ask Questions: When purchasing jewelry, don't hesitate to ask about the hardness of the gemstones. Reputable jewelers will provide this information.

  4. Think About Care: Softer gemstones may require more frequent cleaning and careful handling to maintain their appearance.

  5. Balancing Beauty and Durability: If you're drawn to a gemstone lower on the Mohs Scale, consider it for jewelry pieces that won't be worn daily, such as earrings or pendants.


The Mohs Hardness Scale is a valuable tool for jewelry shoppers, providing insight into the durability and wearability of gemstones. Understanding this scale allows you to make informed decisions when choosing jewelry pieces that will last a lifetime. Whether you're looking for an engagement ring, a necklace, or earrings, considering the hardness of the gemstone ensures that your jewelry will remain beautiful and cherished for years to come. So, next time you're shopping for jewelry, remember to keep the Mohs Hardness Scale in mind to make the perfect choice for your needs and style.

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