The Connection Between Diamond Hardness and Durability

Diamonds are celebrated as the hardest natural material on Earth, ranking 10 on the Mohs scale of mineral hardness, a measurement established by German mineralogist Friedrich Mohs in 1812. This exceptional hardness is part of what makes diamonds so desirable for engagement rings and fine jewelry, symbolizing strength, permanence, and love. Yet hardness alone does not mean a diamond is indestructible.

The Diamonds are the hardest known natural material, resistant to scratches, but they are still vulnerable to chipping or breaking due to their natural cleavage planes. This often surprises buyers who assume that "hardest" means "unbreakable." In reality, hardness only refers to scratch resistance, while overall durability includes toughness (resistance to breaking) and stability (resistance to temperature or chemical change).

This guide explains what makes diamonds hard, how durability works, and the factors you should consider to ensure your diamond remains both brilliant and resilient for a lifetime.

What Is Diamond Hardness?

Hardness refers to how well a material resists scratching. Scientists measure it on the Mohs scale, which ranks materials from 1 to 10. At the very top sits the diamond, ranked 10, making it the hardest naturally occurring substance on Earth.

The reason diamonds score so high on the Mohs scale is due to their unique atomic structure. Each carbon atom in a diamond is bonded tightly to four other carbon atoms in a crystal-like pattern, creating a rock-solid structure that's incredibly difficult to scratch. This atomic structure is a key factor in the diamond's durability, as it makes it resistant to most forms of wear and tear. Only another diamond can scratch a diamond.

This hardness makes diamonds perfect for jewelry that gets worn regularly, such as engagement rings, wedding bands, or bracelets. They're able to withstand most abrasion they might encounter in everyday life, such as rubbing against other jewelry, coming into contact with hard surfaces, or exposure to household chemicals.

However, while hardness explains why scratch-resistant diamonds are, it doesn't cover other aspects of strength, such as breaking or chipping. That's where durability comes in.

What is Diamond Durability?

Durability is a broader term than hardness. Springer it 'as the resistance of geomaterials to deterioration caused by physical, chemical, and biological agents acting in a specific environment. Durability is the capacity of a geomaterial to resist either to weathering processes or the decay caused by anthropogenic activities in a given period of time.' Durability includes three main factors: hardness, toughness, and stability. All three work together to determine how long a diamond can keep its shape, polish, and brilliance.

• Hardness: This is a diamond's ability to resist scratches. As mentioned earlier, diamonds have the highest rating on the Mohs scale, meaning most other materials cannot scratch them. Daily dust, which often contains quartz, won't affect them the same way it might wear down other stones.
• Toughness: Toughness in chemistry is the strength with which the material opposes rupture. One definition of material toughness is the amount of energy per unit volume that a material can absorb before rupturing.' How well a diamond resists breaking, cracking, or chipping when hit. Despite their hardness, diamonds are considered brittle. That's because they have cleavage planes, specific directions in the crystal structure where bonds are slightly weaker. When force strikes these planes at just the right angle, a diamond can chip or even split. For instance, if a diamond ring gets knocked against a hard surface or dropped onto tile, it might not scratch. Still, it could chip or crack, especially along the girdle or corners. This is where the concept of toughness comes into play, as it measures a diamond's ability to resist these types of damage.
• Stability: Stability measures how well a gem tolerates changes in temperature and exposure to chemicals or light. Diamonds are very stable in most environments. They won't fade in sunlight or dissolve in most chemicals. However, extremes in heat or sudden temperature changes can damage them. A good example is thermal shock. If a diamond is exposed to sudden, very high heat and then cooled rapidly, it could fracture. Even house fires, which can reach incredibly high temperatures, have been known to damage diamonds. Although rare, this is a reminder that strong doesn't mean indestructible. Dr. Christopher Baird's explanation can be found.

The Connection Between Hardness and Durability

Diamonds are tough, but that doesn't mean they're immune to damage. There's a difference between resisting scratches and resisting cracks, chips, or breakage. This gap becomes noticeable when you consider how diamonds are handled, shaped, and worn.

Diamond Cut and Shape

The way a diamond is cut plays a significant role in how well it retains its value over time. Well-cut diamonds with balanced proportions are typically stronger, as their symmetry helps distribute mechanical stress evenly. On the other hand, diamonds with thin girdles or sharp corners are more likely to chip, especially when set in exposed positions. Shapes like round brilliant diamonds are naturally sturdier; their rounded edges lack vulnerable points, and their symmetry helps absorb and disperse impact more evenly.

This is supported by a recent study by Khalil et al. (2023), published in Materials Today Communications, which demonstrates that sharp geometries in diamond turning tools result in localized stress concentrations and an increased risk of material failure. The authors note that geometry-induced stress points, such as edges and corners, are primary factors in chip initiation and propagation, confirming why fancy cuts like marquise, pear, or princess are more susceptible to chipping without protective settings..

Inclusions and Internal Weaknesses

Inclusions aren't just visual; they can weaken a diamond's structure. A feather near an edge or girdle may turn into a stress point, increasing the risk of chipping. Surface-reaching fractures are especially critical, as they create fault lines that reduce the toughness of the material.

As noted in HPHT-Treated Diamonds (Springer, 2013): "Surface-reaching cleavages and internal fractures significantly influence the mechanical strength of the diamond crystal. Inclusions near the surface can act as failure initiation sites under stress."

Setting Style

The correct setting can make all the difference in protecting your diamond. Settings that surround or partially shield the stone, such as bezel or half-bezel settings, can help protect against accidental bumps. In contrast, very open or high-profile settings may expose edges or corners, especially in fancy-shaped diamonds. When choosing a setting, consider your lifestyle. If you're active or work with your hands, a protective setting may be a more intelligent choice.

How to Choose a Durable Diamond

If long-term durability is essential to you (and it should be), here are a few key things to look for when selecting a diamond:

• Focus on the Cut Quality
  A high-quality cut isn't just about sparkle; it's also about how well the diamond is shaped and structurally supported. Look for diamonds with medium to slightly thick girdles. Extremely thin girdles can chip easily, especially when the stone is being set in place. Avoid diamonds with overly deep or shallow proportions. Poorly cut diamonds may not distribute force evenly, which can affect durability.
• Review the Clarity and Inclusions
  Take time to review the diamond's clarity grades report. Look beyond the grade and check the inclusion plot to see what's present and where. Large feathers, cavities, or knots near the surface may weaken the stone. Clarity grades like VS1, VS2, or SI1 often feature diamonds that appear clean to the naked eye, while avoiding inclusions that can negatively impact strength. These grades are a sweet spot where value and durability meet.
• Choose the Right Shape for Your Lifestyle
  If you're drawn to intricate shapes, that's completely okay; pay extra attention to how they're arranged. Pear, marquise, heart, and princess cuts should be protected by prongs or bezels that cover their pointed ends. If you're looking for maximum durability with minimal vulnerability, round diamonds are usually the safest bet.
• Work with Experienced Professionals
  Choosing a durable diamond isn't just about reading reports—it takes an experienced eye to spot risks and guide you toward safety and style. Gemologists with professional training can help you find a stone that is both strong and visually stunning. It helps to shop in a place where both quality and transparency are prioritized, so you can trust what you're getting, not just based on the numbers but on years of experience.

Caring for Your Diamond

Even the most beautiful and well-cut diamond needs care. Here are a few simple tips to help extend the life and look of your diamond:

Remove Your Ring for Impact-Prone Activities

If you're about to play sports, lift weights, work with tools, or garden, remove your ring or bracelet. These activities involve a risk of high-impact force or scratching, especially near hard surfaces.

Don't Wipe It Dry

Believe it or not, something as simple as wiping a diamond the wrong way could cause small scratches, especially if there's dust involved. Clean your diamond by rinsing it in mild, soapy water, gently brushing it with a soft brush, then patting it dry with a lint-free cloth. Avoid paper towels or typical fabrics that can rub dust particles against the surface.

Store It Safely

Diamonds can scratch other materials, and they can even scratch each other. Always store your diamond pieces separately, either in soft pouches or lined jewelry boxes with individual compartments, to prevent scratches and damage.

Have Regular Checkups

Once a year, take your jewelry in and have the setting inspected—especially if you wear it daily. A loose prong or slightly shifted stone may not be noticeable right away, but could lead to loss or damage over time.

Find Your Forever Sparkle with Leon Diamonds

Diamonds may be the most rigid natural material known, but true durability extends beyond scratch resistance. A diamond's ability to withstand daily life depends on its overall strength, cut, clarity, shape, and how it's worn and maintained.

By learning the difference between hardness and durability, you're better equipped to choose a diamond that will not only shine brilliantly but also stand the test of time. Whether you're shopping for an engagement ring, a special gift, or simply treating yourself, it's well worth investing in a stone that fits your lifestyle as much as your taste.

To explore a vast jewelry collection of certified, beautifully cut diamonds and get expert help in choosing one that's perfect for you, call Leon Diamonds at 212-302-7327 or visit our showroom in New York City's Diamond District.

Frequently Asked Questions 

What does it mean when a diamond is called the "hardest natural material"?

A diamond's hardness refers to its exceptional resistance to scratching, ranking 10 on the Mohs scale of mineral hardness. This means that only another diamond can scratch it, making it ideal for jewelry that faces daily wear and tear.

Can a diamond chip or break even though it's so hard?

Yes. While diamonds are tough and resist scratches, they are also brittle and can chip, crack, or break if struck at the right angle, especially along their cleavage planes or at thin edges and corners.

What's the difference between diamond hardness and diamond durability?

Hardness is a diamond's ability to resist scratches, while durability is a broader concept that includes hardness, toughness (resistance to breaking or chipping), and stability (resistance to heat and chemicals). A diamond can be hard, but it is still vulnerable to chipping or cracking.

How do cut, shape, and inclusions affect a diamond's durability?

Diamonds with well-balanced cuts and medium to thick girdles are generally more durable. Shapes with pointed corners, such as marquise, pear, or princess cuts, are more prone to chipping, primarily if inclusions are located near the edges or surface.

What is the best way to protect my diamond from damage?

Choose protective settings, such as bezel or half bezel, for vulnerable shapes. Avoid wearing your diamond during high-impact activities. Store it separately from other jewelry and have it checked regularly by a jeweler to ensure the setting is secure.

Does diamond care and cleaning affect its long-term durability?

Yes. Proper cleaning with mild soap and a soft brush prevents scratches from dust or grit. Avoid wiping diamonds dry with paper towels or rough fabrics, and always store them in soft pouches or lined compartments to avoid accidental scratches or chips.