What is HPHT diamond treatment?

HPHT diamonds are often confused with HPHT-treated diamonds. While HPHT diamonds are grown in a lab, HPHT color treatment refers to a process used to enhance the color of natural or lab-grown diamonds. HPHT Lab-Grown Diamonds: These are created entirely in a lab using the HPHT process. HPHT-Treated Diamonds: These are natural or lab-grown diamonds subjected to HPHT conditions to improve their color, typically turning brownish diamonds into colorless or near-colorless ones. The key difference is the purpose: HPHT lab diamonds refers to the growing process (which could also include improvements to the diamond’s color), whereas HPHT-treated diamonds indicates that the gemstone has undergone an additional process for color enhancement as part of the growth process.

How long does it take to grow a diamond in a lab?

The growth time for lab grown diamonds varies depending on the method used and the desired size. HPHT diamonds: Typically take several days to a few weeks. CVD diamonds: Usually require several weeks to grow a gem-quality diamond. Post-growth treatments, such as polishing and cutting, can add additional time before the diamond is ready for the market.

Which is better, a CVD or HPHT diamond?

HPHT diamonds may offer more consistent color without additional treatment, while CVD diamonds allow for finer control over clarity and production conditions. Both methods yield high-quality diamonds indistinguishable from natural diamonds.

Are CVD diamonds real?

Yes, CVD diamonds are real diamonds. They have identical chemical, physical, and optical properties as natural diamonds and are graded according to the same standards.

Are HPHT diamonds real?

Yes, HPHT diamonds are real diamonds. They share the same chemical composition, hardness, and brilliance as natural diamonds.

Do CVD diamonds pass a diamond tester?

Yes, CVD diamonds pass diamond testers . These devices detect the thermal conductivity of diamonds, which is identical in natural and lab-grown varieties.

What is the CVD diamond price?

The cost of lab grown diamonds can vary based on factors like carat weight, color, and clarity. As CVD diamonds are lab diamonds, they are generally more cost effective than natural diamonds of similar quality.

What is the HPHT diamond price?

Because they are lab grown, HPHT diamonds are typically more affordable than natural diamonds of similar quality. Prices vary based on size, cut, and clarity.

Can lab grown diamonds be made in any size?

While lab grown diamonds can be made in various sizes, larger diamonds take longer to grow and are more challenging to produce. Most lab diamonds are created within a specific size range to balance quality and efficiency.

Can lab grown diamonds be customized?

Yes, lab grown diamonds offer opportunities for customization , including size, shape, and even color. This level of control is one advantage of producing diamonds in a laboratory.

Brilliant Earth

How Are Lab Diamonds Made?

Lab grown diamonds are created using two primary methods, High Pressure High Temperature (HPHT) and Chemical Vapor Deposition (CVD), each designed to replicate the natural conditions under which diamonds form.

Chemical Vapor Deposition (CVD): CVD diamonds are lab diamonds formed through a Chemical Vapor Deposition process, which uses carbon gas to grow diamonds in a controlled environment. In CVD, a seed diamond is placed inside a vacuum chamber filled with heated hydrogen and methane-rich gas. When the chamber reaches a certain temperature, the gas molecules break down, and layers of crystallized carbon form around the seed, creating a larger diamond.
High Pressure High Temperature (HPHT): An HPHT diamond is a type of lab-grown diamond created by replicating the natural process that forms diamonds deep within the Earth's mantle. By exposing carbon to high pressure (approximately 5–6 GPa) and extreme temperatures (1,300–1,600°C) within a controlled environment, diamond crystals are formed.

These two methods allow for precise control over the growing process, resulting in high-quality lab created gemstones that are identical to natural, mined diamonds.

The differences between natural diamonds, HPHT-grown diamonds, and CVD-grown diamonds are undetectable to the naked eye. At Brilliant Earth, we offer lab reports on all our diamonds for more information on a diamond’s origin and characteristics.

CVD Diamond Process

CVD diamond growth relies on Chemical Vapor Deposition, which involves breaking down carbon gases to form diamond crystals. Here’s an overview of how the process works:

Seed Placement: A disc containing 15-30 small diamond seeds (tiny pieces of natural or lab diamond) is placed in the growth chamber.
Gas Activation: Inside the chamber, a plasma ball of superheated methane and hydrogen gases is generated.
Heat Increase: The chamber temperature is raised to 700-1200°C.
Diamond Formation: Activated methane and hydrogen gases adhere to the seeds, repeatedly forming carbon layers over days or weeks, replicating the crystal structure of the original diamond seed and forming a pure diamond crystal.
Monitoring and Cutting: Technicians monitor the diamond growth and remove the crystals once they are the desired size and ready for cutting. The lab diamond is then polished and shaped, preparing them for jewelry settings.

This precise process enables manufacturers to control factors like growth rate, clarity, and color for optimal quality.

HPHT Diamond Process

The HPHT process involves three key stages:

Creating the Environment: A specialized High-Pressure High-Temperature diamond machine includes a cell made up of three parts: The top layer contains the carbon material; the middle layer holds the metal catalyst, such as nickel or cobalt; and the bottom layer is where the diamond seed crystal is placed.
Diamond Formation: This capsule is subjected to extremely high pressure and heat. The carbon begins to crystallize, forming diamond structures, with the catalyst accelerating this process.
Cooling and Cutting: Once the diamond crystals have formed, the environment is slowly cooled, and the diamonds are extracted, cut, and polished.

This process closely mimics the natural formation of diamonds, which occurs over billions of years beneath the Earth's surface.

CVD vs. HPHT Diamonds: What’s the Difference?

CVD and HPHT diamonds are the two main methods for growing lab diamonds. The primary differences between CVD and HPHT diamonds lie in their production techniques and conditions:

Formation Method: HPHT replicates natural diamond formation under simulated high-pressure, high-temperature conditions like those found within the Earth, while CVD grows diamonds layer by layer in a gas-filled chamber.
Growth Conditions: CVD diamonds are developed in a lower-pressure environment with controlled carbon gas exposure, while HPHT diamonds are grown under extreme pressure (5-6 GPa).
HPHT Treatment: Some CVD lab-grown diamonds are subjected to HPHT conditions to improve their color, typically turning brownish diamonds into colorless or near-colorless ones.
Diamond Size: HPHT is generally better for producing smaller, higher-quality diamonds, while CVD is suitable for larger diamonds.
Inclusions: HPHT diamonds may contain metal inclusions due to the catalyst used, whereas CVD diamonds typically show fewer inclusions. It's important to note that lab diamonds undergo the same grading process as natural diamonds, including an assessment of the four Cs.
Color Quality: HPHT diamonds often require less post-growth color treatment compared to CVD diamonds.

What Are Lab Grown Diamonds Made Of?

Lab grown diamonds are composed of carbon, just like natural diamonds. The carbon atoms are arranged in a crystal lattice structure, which gives diamonds their unparalleled hardness and brilliance.

During the growth process, trace elements may be introduced either intentionally or as a byproduct of the production environment. These elements can affect the diamond’s color. For instance, nitrogen can produce a yellow tint, while boron may result in blue diamonds.

Key Components in the Growth Process:

1. Diamond Seed

The diamond seed serves as the foundation for growth.
This seed is typically a thin slice of pre-existing diamond, either natural or lab grown, that provides the crystalline structure needed for diamond formation.

2. Carbon Source

In HPHT, carbon comes from graphite or other carbon-rich materials.
In CVD, carbon is derived from hydrocarbon gases like methane and hydrogen.

3. Trace Elements

In some cases, elements such as nitrogen, boron, or hydrogen may be present.
These elements can influence the diamond’s color, with hydrogen and nitrogen creating yellow hues and boron producing blue tones.

Lab Diamond Guide

Where Are Lab Grown Diamonds Made?

Lab grown diamonds are made in laboratories, where controlled conditions replicate the forces that create diamonds in nature. Unlike natural diamonds, which form deep within the Earth’s mantle, lab diamonds are grown using advanced technologies in a carefully monitored environment. These laboratories are equipped with cutting-edge machinery, such as HPHT presses or CVD chambers, to facilitate the diamond growth process. The laboratory environment also allows for customization, enabling the creation of diamonds with specific sizes, shapes, and qualities.

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