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The Physical and Optical Properties of Lab-Grown Diamonds

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When it comes to the allure and desirability of diamonds, both their physical and optical properties often take centre stage.

From the hardness that withstands everyday wear and tear to the fire and brilliance that catch your eye, each characteristic contributes to the gem’s overall appeal.

In today’s discussion, we are going to delve into the fascinating world of lab-grown diamonds, focusing on both their physical and optical properties.

What is a Lab-Created Diamond?

If you’ve ever marvelled at the sparkling allure of a diamond, you might be surprised to learn that not all diamonds come from deep within the Earth.

Some diamonds are created.

These man-made diamonds, commonly known as lab-grown diamonds, are created in meticulously controlled laboratories. A lab-created diamond is a gemstone that’s chemically, physically, and optically identical to a natural diamond.

In terms of their formation, lab-grown diamonds are crafted primarily through two pivotal techniques: High-Pressure High Temperature (HPHT) and Chemical Vapour Deposition (CVD). HPHT involves subjecting a diamond seed to intense temperatures and pressures, mimicking the earth's natural diamond-creating conditions. On the other hand, CVD involves the strategic placement of a diamond seed in a chamber filled with specific gases. When energised, these gases release carbon atoms that adhere to the diamond seed, growing it progressively. Both methods yield diamonds of impeccable quality, challenging their naturally sourced counterparts in terms of brilliance and properties, all while being more sustainable and cost-effective.

Lab Grown Diamonds: Hardness, Toughness, Stability & Fire, Scintillation and Brilliance

When it comes to choosing a diamond, whether it’s for an engagement ring or as a special gift, you might find yourself between two options.

To opt for a natural diamond or a lab-grown one?

The good news is, with lab-grown diamonds, you don’t have to compromise on quality, beauty, or ethics; they are virtually the same as mined ones.

Before reviewing the physical and optical properties of lab-grown diamonds, it's important to understand the two categories of properties we will be discussing. Physical properties describe the palpable, measurable characteristics of a diamond like hardness, toughness, and stability. On the other hand, optical properties, like fire, scintillation, and brilliance, relate to how diamonds interact with light to create their characteristic sparkle and lustre.

Physical Properties

In the gem world, hardness refers to a stone’s degree of resistance to scratches and abrasions.

Both mined and lab-grown diamonds rank at the top of the Mohs scale (10), which means they're incredibly resistant to scratches.

In contrast, "softer" gemstones, like opals and pearls, are lower on the Mohs scale. While they have their own unique beauty, they can be more prone to scratches and might need a bit more care in handling and wear.

For those seeking a gemstone that can withstand daily activities without showing wear, both lab and mined diamonds fit the bill perfectly.

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Fig 1 - Graph showcasing the relative hardness of different gemstones on the Moh's scale

.In contrast, "softer" gemstones, like opals and pearls, are lower on the Mohs scale. While they have their own unique beauty, they can be more prone to scratches and might need a bit more care in handling and wear.

For those seeking a gemstone that can withstand daily activities without showing wear, both lab and mined diamonds fit the bill perfectly.

Toughness in a gem refers to its ability to resist chipping, cracking, or breaking.

Diamonds, with their unparalleled hardness due to the strong bonds within their crystal lattice structure, do have a considerable level of toughness. However, they are not immune to breaking - while they can largely resist daily wear impacts, they're not invincible. When hit along a specific angle, or a cleavage plane, a diamond can break.

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Fig 2. - Visual exmaple of a cleaveage plane. 

.Cleavage planes are inherent planes in the diamond where the atomic bonding is weaker, making it more susceptible to breaking if struck with force in these areas. A simple analogy to this is wood; cutting wood at random can seem a difficult task, but when cut down at the correct angle, it is “split” relatively evenly, and easily.

Lab-grown diamonds have the same toughness as mined diamonds, and similarly so, possess cleavage planes as well.

A gemstone's stability refers to its inherent resilience against exposure to light, humidity, temperature changes, and chemicals.

Unsurprisingly, lab-grown diamonds exhibit the same high degree of stability as mined diamonds. Lab-grown diamonds are impervious to most chemicals, remain stable under significant temperature fluctuations, adeptly handle moisture and humidity, and, of course, do not fade under light.

Optical Properties 

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Fig 3. - Brilliance, Fire & Scintillation are three optical properties of diamonds. Brilliance referes to the diamond's ability to reflect white light, fire referes to the diamond's ability  to disperse light into different colors, and scintillation refers to the dynamic play of light when a diamond moves. 

Brilliance refers to a diamond's ability to reflect both internal and external white light. A diamond that exhibits a high degree of brilliance gleams with intense white light reflections, making it appear vibrant and lively, whereas one with lesser brilliance can seem dull.

With lab-grown diamonds, their brilliance mirrors that of their mined counterparts - thanks to their identical atomic structures. However, it's crucial to note that the cut of a diamond, whether natural or lab-grown, plays a pivotal role in maximising this brilliance. No matter if the diamond was grown in a lab, or mined from the earth, if its cut is poor, its brilliance would be compromised.

The fire in lab-grown diamonds, which refers to the dispersion of light into various colours, is practically indistinguishable from that of natural diamonds, and this is because both types of diamonds have the same refractive index and dispersion characteristics.

When having an identical cut to a mined diamond, a lab-grown-diamond promises to mesmerise with the same play of colours to its natural occurring counterpart.

Last, but certainly not least, we have scintillation

Scintillation refers to the dynamic play of light that is observed when a diamond moves, encompassing both the sparkling bright flashes and contrasting dark areas. Put simply, it’s the “sparkle” that you see when you move a diamond around in light.

When it comes to lab-grown diamonds, the scintillation is the same as mined diamonds. This is because the faceting techniques for both types of diamonds are the same; they aim to maximise scintillation, leading to that mesmerising sparkle.

In summary, the world of gemology reveals that lab-grown and mined diamonds are nearly indistinguishable in terms of their physical and optical properties.

From their unmatched hardness and stability to their captivating fire, scintillation, and brilliance, both varieties stand as great examples of nature's beauty and human ingenuity.

As with every gemstone, the choice between man-made or lab-grown rests upon personal preferences and values, but it's heartening to know that, in terms of sheer quality and aesthetics, lab-grown diamonds offer the same enchanting allure as their natural counterparts.

This makes them not only a sustainable choice but also a testament to the advancements in gemological sciences, proving that beauty, ethics, and technology can harmoniously coexist.

As specialists in the lab-grown diamond industry, we invite you to visit our local showroom in Calgary and experience the marvels of lab-grown diamonds firsthand. Our experts are on-site to answer any questions and guide you through the unique attributes of these gemstones, ensuring you make an informed and confident purchase for your special occasions.