Natural diamonds formed deep within the Earth through geological processes, with many dating back billions of years. Advances in technology have now made it possible to grow diamonds in controlled laboratory environments. 

Today, there are two main methods used to create lab-grown diamonds: High Pressure High Temperature (HPHT) and Chemical Vapour Deposition (CVD). While both methods produce real diamonds, the way the crystal grows is different. 

To help you better understand your options, here is a guide to the different types of lab-grown diamonds, how they are created and how they compare. 

What Are the Different Types of Lab-Grown Diamonds?

There are two main types of lab-grown diamonds based on the process used to grow them: 

1. HPHT diamonds – High Pressure High Temperature 
2. CVD diamonds – Chemical Vapour Deposition  

Both methods produce laboratory-grown diamonds with essentially the same chemical, physical and optical properties associated with natural diamond. 

The main difference is the environment in which the diamond crystal grows. 

Diamond simulants such as cubic zirconia and moissanite are different. They may resemble diamonds visually, but they are different materials and should not be classified as types of lab-grown diamonds. 

What Are Lab-Grown Diamonds Called?

Lab-grown diamonds go by several names, which can be a common source of confusion. 

Common terms include: 

• Lab-grown diamonds  
• Laboratory-grown diamonds  
• Lab-created diamonds  
• Laboratory-created diamonds  
• Man-made diamonds  
• Synthetic diamonds  

“Synthetic diamond” is also used as a technical gemmological term, although it can sometimes sound misleading to shoppers because lab-grown diamonds are not imitation diamonds. 

You may also see diamonds described according to their growth method as HPHT diamonds or CVD diamonds. 

What they are not is a diamond simulant. 

Cubic zirconia and moissanite are simulants—materials designed to resemble diamond but with different chemical and physical properties. 

A lab-grown diamond is diamond. A diamond simulant is not. 

Are Lab-Grown Diamonds Real Diamonds? 

Yes. A lab-grown diamond has the same diamond crystal structure and essentially the same chemical and physical properties as a natural diamond. 

It is not an imitation. 

The main difference is origin. A natural diamond formed deep within the Earth through geological processes, while a lab-grown diamond is produced in a controlled environment using either the HPHT or CVD growth process. 

Lab-grown diamonds can be independently evaluated by gemmological laboratories, and their reports identify them as laboratory-grown. 

To the unaided eye, a high-quality lab-grown diamond can look the same as a comparable natural diamond. Specialist equipment and gemmological analysis are generally required to identify its laboratory-grown origin and growth characteristics. 

CVD Lab-Grown Diamonds 

CVD stands for Chemical Vapour Deposition. 

Rather than recreating the extremely high pressures associated with natural diamond formation, CVD uses a low-pressure chamber containing carbon-bearing gases to grow diamond material gradually onto a diamond seed.

How Are CVD Diamonds Made?

A CVD diamond is grown inside a vacuum chamber. 

First, a diamond seed—a thin piece of diamond—is placed inside the chamber. The chamber is then filled with a carbon-containing gas mixture, commonly including methane and hydrogen. 

Energy is introduced into the chamber to create a plasma. This breaks down the gas and allows carbon-containing material to settle onto the diamond seed. 

The diamond then grows layer by layer over time until sufficient crystal material has formed. 

After growth, some CVD diamonds may undergo additional treatment to improve characteristics such as colour before being cut and polished. 

HPHT Lab-Grown Diamonds

HPHT stands for High Pressure High Temperature. 

The process uses extremely high pressure and temperature to recreate some of the conditions associated with diamond formation deep within the Earth. 

How Are HPHT Diamonds Made? 

The HPHT process begins with a small diamond seed placed inside a specialised growth cell along with a carbon source. 

The growth cell is placed into a powerful press, where it is exposed to extremely high pressures and temperatures. 

Under these conditions, the carbon dissolves and crystallises onto the diamond seed. 

Over time, the crystal grows until a larger piece of diamond material is formed. It can then be cut, polished and evaluated for jewellery use. 

HPHT was also the first laboratory-growth method to successfully produce gem-quality diamonds.

HPHT vs CVD: Which Type of Lab-Grown Diamond Is Better? 

Both HPHT and CVD produce real diamonds with essentially the same fundamental chemical and physical properties. The differences are mainly in how the crystals grow. 

HPHT diamonds are typically grown at pressures of around 5–6 GPa and temperatures of approximately 1,300–1,600 degrees Celsius. The process recreates high-pressure and high-temperature conditions and can produce crystals with a characteristic cuboctahedral growth form. Some HPHT-grown diamonds may also contain small metallic inclusions associated with the growth environment. 

CVD diamonds are grown layer by layer from carbon-containing gases in a low-pressure chamber. Their crystal growth characteristics differ from HPHT diamonds, and some CVD stones undergo post-growth treatment to improve their colour. 

For a buyer, neither method is automatically better. 

What matters more is the quality of the individual diamond, including its: 

• Cut  
• Colour  
• Clarity  
• Carat weight  
• Overall appearance  
• Independent laboratory report  

If you are comparing stones, our diamond buying guide explains how cut, colour, clarity and carat weight affect diamond quality and appearance.

Rather than choosing a diamond simply because it is HPHT or CVD, compare individual stones and review the accompanying report. You can also see how we select a diamond when assessing the quality of different options.

Lab-Grown Diamonds vs Diamond Simulants 

This is one of the most important distinctions to understand when shopping for a diamond. 

A lab-grown diamond has essentially the same chemical structure and physical properties as a natural diamond. 

A diamond simulant only imitates the appearance of a diamond. 

Common simulants include cubic zirconia and moissanite. 

They may provide a diamond-like appearance at a lower price, but neither is actually diamond. 

Cubic Zirconia 

Cubic zirconia is a synthetic gemstone made primarily from zirconium dioxide. 

It can resemble diamond visually, particularly when new, but it is considerably softer than diamond and is more susceptible to scratching and wear over time. 

Cubic zirconia is generally one of the least expensive diamond simulants. 

Moissanite 

Moissanite is made from silicon carbide. 

It is considerably harder and more durable than cubic zirconia, making it suitable for everyday jewellery. 

Moissanite also has a different optical appearance from diamond and can display stronger rainbow-coloured flashes under certain lighting conditions. 

Although moissanite can look similar to diamond, it is a separate gemstone and is not a lab-grown diamond.

Lab-Grown vs Natural Diamonds 

Side by side, a lab-grown diamond and a natural diamond of comparable quality can appear essentially the same to the unaided eye. 

Both have diamond's characteristic crystal structure, hardness and brilliance. 

The main differences are their origin, rarity and market pricing. 

Natural diamonds form through geological processes deep within the Earth and are naturally scarce. 

Lab-grown diamonds are produced using controlled HPHT or CVD technology and can typically be purchased at a lower upfront price than a comparable natural diamond. 

This can allow some buyers to choose a larger stone or higher specifications while staying within the same budget, particularly when comparing diamonds for engagement rings.

Their markets also behave differently. Natural diamonds derive part of their positioning from geological rarity, while lab-grown diamond supply can increase as manufacturing technology and production capacity develop. 

Neither option is automatically right for everyone. 

The choice depends on whether you place greater importance on factors such as natural origin and rarity or on achieving a particular size and quality at a lower upfront price. 

How Big Can Lab-Grown Diamonds Get? 

Lab-grown diamonds are now available in sizes that would be exceptionally rare and expensive in comparable natural diamonds. 

Both HPHT and CVD technology can produce gem-quality diamonds well above five carats, and production capabilities continue to develop. 

This is one practical reason some buyers choose lab-grown diamonds. A larger centre stone may be available at a lower upfront price than a natural diamond of similar size and quality. 

Larger lab-grown diamonds will generally increase in price as carat weight and quality increase, although pricing also depends on factors such as cut, colour, clarity and current market conditions. 

A Short History of Lab-Grown Diamonds 

Laboratory-grown diamonds are not a recent development. 

Scientists successfully produced diamond material using laboratory techniques during the 1950s, with both HPHT and CVD research developing during this period. 

HPHT became the first method to successfully produce gem-quality laboratory-grown diamonds, while many early synthetic diamonds were primarily created for industrial applications such as cutting, drilling and grinding. 

CVD diamond research also dates back to the 1950s, although later advances made it possible to grow increasingly consistent and higher-quality CVD diamond material suitable for jewellery. 

What has changed most in recent decades is the scale, consistency and quality of production. 

Lab-grown diamonds are now available across a wide range of sizes, colours and quality levels suitable for engagement rings, wedding jewellery and other fine jewellery.

Explore Lab-Grown Diamonds at The Diamond Guys 

Ready to see lab-grown diamonds in person? 

Book an appointment at our Melbourne showroom to compare lab-grown diamond options and discuss HPHT and CVD stones with our team. 

You can also call (03) 9526 8421 to discuss your requirements.