Gemstone Hardness: What is the Mohs Hardness Scale
When it comes to choosing a gemstone for jewelry, beauty is just one factor—durability matters just as much. Whether you’re selecting an engagement ring, a daily-wear pendant, or a statement bracelet, understanding a gemstone’s hardness ensures it can withstand scratches, chips, and everyday wear.
That’s where the Mohs Hardness Scale comes in. Developed over 200 years ago, this scale helps gemologists, jewelers, and buyers compare the scratch resistance of different minerals. In this guide, we’ll break down what the Mohs Scale is, how it works, and why it’s essential for selecting the right gemstone.
What is the Mohs Hardness Scale?
What is the purpose of its invention? How does the Mohs Scale work? This part will give you some hints.
The Origin of the Mohs Scale
In 1812, German mineralogist Friedrich Mohs created a simple yet effective way to measure mineral hardness. His method was based on one key principle: a harder material can scratch a softer one, but not vice versa.
Instead of relying on complex scientific instruments, Mohs compared minerals by testing which ones could scratch others. He then ranked them on a scale from 1 (softest) to 10 (hardest), with each number representing a key reference mineral.
How Does the Scale Work?
The Mohs Scale is a relative measure, meaning it compares minerals to one another rather than assigning absolute hardness values. For example:
- Talc (1) is the softest—it can be scratched by even a fingernail.
- Diamond (10) is the hardest—it can scratch every other mineral on the scale.
Mohs Hardness Scale for Gemstones: What You Need to Know
Here’s a quick reference table for the Hardness Levels of Popular Gemstones:
|
Mohs Hardness |
Mineral/Gemstone |
|
1 |
Talc |
|
2 |
Gypsum |
|
3 |
Calcite |
|
4 |
Fluorite |
|
5 |
Apatite |
|
6 |
Orthoclase (Feldspar) |
|
7 |
Quartz (Amethyst, Citrine) |
|
8 |
Topaz |
|
9 |
Corundum (Ruby, Sapphire) |
|
10 |
Diamond |
While this scale is incredibly useful, it’s important to note that the jumps between levels aren’t equal. For example, diamond (10) is four times harder than corundum (9), even though they’re just one number apart.
Hardness Levels of Popular Gemstones
What’s the meaning of each number? Here is the explanation:
- Talc (1) – The softest mineral, easily scratched. Not used in jewelry.
- Amber (2-2.5) – Organic and delicate, best for low-impact pieces like earrings.
- Pearl (2.5-4.5) – Requires careful handling due to its softness.
- Opal (5.5-6.5) – Beautiful but prone to scratches; better in protective settings.
- Quartz (7) – Includes amethyst, citrine, and rose quartz. Durable enough for rings.
- Topaz (8) – A great choice for everyday wear.
- Corundum (9) – Rubies and sapphires are extremely scratch-resistant.
- Diamond (10) – The hardest known natural material, ideal for engagement rings.
Hardness vs. Toughness: Not the Same Thing
A common misconception is that a high Mohs rating means a gemstone is indestructible. However, hardness only measures scratch resistance, not toughness (resistance to breaking or chipping).
For example:
- Moissanite (9.25) is nearly as hard as diamond but has greater toughness, making it less likely to chip.
- Diamond (10) is the hardest but can still shatter if hit at the right angle due to its cleavage planes.
This is why jewelry settings matter—even a hard gemstone needs proper protection to last a lifetime.
Choosing the Right Gemstone from Romalar
Understanding the Mohs Scale helps you pick a gemstone that matches your lifestyle. If you’re looking for a daily-wear ring, aim for 7 or higher (quartz, topaz, sapphire, or diamond). For earrings or pendants, softer stones like pearls or opals can work with proper care.
If you love the brilliance of diamonds but want a more affordable yet durable alternative, consider Moissanite—it’s nearly as hard and even tougher in some cases.
At Romalar, we specialize in high-quality gemstone jewelry designed to last. Whether you’re seeking a classic diamond, a vibrant sapphire, or a modern Moissanite piece, our collections combine beauty, durability, and expert craftsmanship.
Explore Romalar’s exquisite gemstone ring today -- where elegance meets endurance.