What is Lab Grown Diamond?

HPHT vs CVD Differences in Lab-Grown Diamonds

Lab-grown diamonds are primarily produced using two methods: HPHT (High Pressure High Temperature) and CVD (Chemical Vapor Deposition). Both processes create diamonds with the same carbon crystal structure as natural diamonds, meaning their physical and chemical properties are essentially identical.

However, the two methods differ significantly in terms of growth environment, crystal formation process, and internal characteristics such as color and inclusions. These differences can influence the final appearance and quality of the diamond.

HPHT Method (High Pressure High Temperature)

The HPHT method replicates the extreme conditions under which natural diamonds form deep within the Earth. It uses high pressure and high temperature to transform carbon into diamond crystals.

How it works

• Uses carbon sources such as graphite
• Applies extremely high pressure (around 5–6 GPa)
• Operates at high temperatures (approximately 1,300–1,600°C)
• Uses metal catalysts such as iron or nickel
• Carbon dissolves and recrystallizes around a diamond seed

Key characteristics

• Crystal structure closely resembles natural diamonds
• Relatively fast growth process
• May exhibit yellow or brown hues due to nitrogen impurities
• High-quality colorless stones are more expensive to produce

Typical applications

• Small to medium-sized jewelry diamonds
• Industrial applications such as cutting and polishing tools

CVD Method (Chemical Vapor Deposition)

The CVD method produces lab-grown diamonds by breaking down carbon-rich gases and depositing carbon atoms layer by layer onto a diamond seed inside a vacuum chamber.

How it works

• Uses methane (CH₄) and hydrogen (H₂) gases
• A plasma is generated inside a vacuum chamber
• Carbon atoms are separated from gas molecules
• Carbon is deposited layer by layer onto a substrate

Key characteristics

• High level of control over purity and clarity
• Suitable for growing larger diamonds
• Often achieves high color grades (D–F range)
• May require post-growth HPHT treatment to improve color

Typical applications

• Medium to large jewelry-grade diamonds
• Mainstream production of high-quality lab-grown diamonds

Comparison: HPHT vs CVD

Lab-Grown Diamond Quality Grading: The 4Cs

Regardless of whether a diamond is produced using HPHT or CVD, its value is ultimately evaluated using the 4Cs: Cut, Color, Clarity, and Carat.

You can learn more about diamond grading here: Diamond 4Cs (Carat Weight and Value Explained)

• Cut: Determines brilliance and sparkle
• Color: The closer to colorless, the higher the value
• Clarity: Fewer inclusions indicate higher quality
• Carat: The weight and size of the diamond

FAQ

What is a lab grown diamond?

A lab grown diamond is a real diamond created in a controlled laboratory environment. It has the same chemical composition, crystal structure, hardness (10 on the Mohs scale), and optical brilliance as a natural diamond. The only difference is origin—natural diamonds form underground, while lab grown diamonds are produced using technologies such as HPHT and CVD.

Are lab grown diamonds cheaper?

Yes. They typically cost significantly less than natural diamonds of the same size and quality.

Can you tell the difference between lab grown and natural diamonds?

No. They look identical to the naked eye. Only specialized laboratory equipment can identify their origin.

Do lab grown diamonds lose value?

They generally have lower resale value than natural diamonds, but offer better upfront value for most buyers.

Which certification is better, IGI or GIA?

Both are reputable. See our full comparison: IGI vs GIA.