Mohs Hardness Scale: Most Durable Gems for Everyday

Have you ever wondered how scientists determine a gemstone’s durability? They use something called the Mohs hardness scale. If you love jewelry and gemstones, you’ve probably heard of it – a scale from 1 to 10, dictating how easy or difficult it is to scratch a mineral. The higher the number, the harder the mineral. It’s a simple but handy way to specify relative hardness.

Read on for an in-depth guide to the Mohs scale, how it works, and which gemstones rank high enough for daily wear.


What Is the Mohs Hardness Scale?

German chemist and mineralogist Friedrich Mohs (1773-1839) developed the eponymous scale in 1892. It determines how scratch-resistant minerals are, ranking them on a scale of 1 to 10 based on overall hardness.

Minerals with a higher ranking can scratch those with a lower ranking. For example, a diamond (10), the hardest-known mineral, can scratch all others. Talcum (1), the softest clay mineral, can be scratched by others with higher rankings.


How the Mohs Hardness Scale Works

To rank a mineral’s hardness, mineralogists scratch its surface with another mineral of known hardness. If it scratches the surface, it’s harder; if not, it’s softer. For the in-between cases, they work their way up the scale.

The Mohs scale is a useful tool for quickly identifying minerals in the field. While not perfect, for many collectors and enthusiasts, it’s a simple way to gain valuable information.


Popular Gemstones from Hardest to Softest

Let’s pan the spotlight over to some of the hardest gems used in the jewelry industry.


Diamond (10)

No surprises here. Deemed the hardest mineral on earth, only a diamond can scratch another diamond. Its extreme hardness and durability make it a popular choice for applications requiring long-lasting wear and abrasion resistance.

Diamonds are 99.95% carbon in an isometric crystalline structure – a driving factor behind their exceptional properties. Their rarity, unparalleled hardness, and brilliance have fascinated people from all social classes for thousands of years. The use and demand for diamonds began around the fourth century BC and has continued to grow ever since. They symbolize love and commitment, thus becoming the most popular gemstone for engagement rings. Eye-clean diamonds also represent wealth, high status, and the ability to manifest abundance.


Ruby (9)

Ranking 9 on the Mohs scale, rubies are incredibly durable gemstones. They exhibit exceptional toughness and no cleavage, meaning rubies will not break along specific planes when struck.

Rubies are a variety of the mineral corundum. Their deep red, bloody color comes from traces of chromium in their composition. Ancient civilizations used rubies as talismans, believing the gem brought health, wisdom, and power to their bearers. Today, rubies – especially Burmese rubies – remain coveted in the jewelry industry, often set in earrings, bracelets, and necklaces. They are also an excellent alternative to diamonds for engagement rings.


Sapphire (9)

Sapphires rank a nearly perfect 9 out of 10 on the Mohs hardness scale. This level of hardness means sapphires can withstand daily wear and tear, making them a wise choice for jewelry, including engagement rings. Sapphires come in an array of stunning colors, with blue being the most well-known and valuable.

Sapphires are also a variety of corundum. The combination of beauty, rarity, and durability have made them a long-time favorite of the wealthy and royalty, as seen on the ring fingers of the previous and current Princess of Wales.


Topaz (8)

Topaz has a hardness between quartz and corundum, making it durable enough for everyday wear. This silicate mineral forms in igneous rocks under high temperatures and pressures, with the best specimens coming from Brazil and Sri Lanka.

The most valued topaz color, called imperial topaz, is reddish orange. Natural blue topaz is also desirable due to its rarity compared to yellow, orange, brown, and colorless topaz.

The stone’s abundance, affordability, and broad spectrum of colors have made it a staple in the jewelry industry. People often substitute topaz for more expensive gems.


Emerald (7.5)

Emeralds rank 7.5 on the Mohs hardness scale. Although relatively durable, their hardness is not on par with other precious gemstones like diamonds, rubies, and sapphires.

Still, emeralds make other gems green with envy. They owe their eye-catching color to the traces of chromium and vanadium in their chemical composition. Their signature hue ranges from a bluish-green to a yellow-green shade. The most sought-after colors are pure green and bluish-green, with vivid color saturation and a not-too-dark tone. The color should be evenly distributed with no zoning.

For centuries, people have prized emeralds for their beauty and rarity, often incorporating them into statement jewelry pieces like engagement rings, necklaces, and earrings. Wearing them and walking into a room full of people will surely make heads turn.


Amethyst (7)

Amethyst is a captivating purple variety of quartz. It ranks 7 on the Mohs hardness scale, which means it’s not as sturdy as the gems mentioned above, but it’s still durable enough for everyday jewelry. Its hue can range from pale lilac to deep purple, depending on trace elements present.

Amethyst is one of the most popular affordable gems in the world. The demand stems from its beauty, considerable abundance, and resilience to everyday wear and tear. It’s also a desirable gemstone for its aesthetic and spiritual properties. The power of amethyst encompasses bringing calm and comfort, easing pain, and relieving stress.


Takeaway: Choose Gemstones Ranked 7 or Higher

Now you have the basics of the Mohs hardness scale under your belt. The scale ranks minerals from 1 to 10 based on scratch resistance, with 1 being the softest and 10 being the hardest.

If you’re wondering which gemstone is durable enough for you or a special someone, remember that a higher Mohs ranking means the stone can better withstand scratches and abrasion from everyday wear and tear. Stones with a Mohs hardness of 7 or higher, such as the six examples above, are well-suited for every day. Of course, if you want optimal durability, you can never go wrong with diamonds!