How are lab grown diamonds made?

How are lab-grown diamonds made?

Lab-grown diamonds are cultivated in controlled environments that replicate the natural conditions in which diamonds form beneath the Earth’s surface. There are two primary methods used to create these diamonds: Chemical Vapor Deposition (CVD) and High Pressure High Temperature (HPHT). Both techniques produce genuine, high-quality diamonds that are chemically and physically identical to their mined counterparts.

In the CVD process, a tiny diamond seed is placed inside a sealed chamber filled with carbon-rich gas. The chamber is heated to extremely high temperatures, causing the gas to ionize. As carbon atoms break apart, they adhere to the diamond seed, gradually crystallizing into a fully formed diamond over the course of a few weeks.

In the HPHT process, pure carbon is placed inside a metal capsule and subjected to extreme heat and pressure through powerful electric pulses. These conditions mimic the natural diamond formation deep within the Earth's mantle. Over time, the carbon atoms break down and rearrange into a crystalline structure, forming a diamond. While trace amounts of metal from the process may remain within the diamond, they are typically microscopic and invisible to the naked eye.

Detailed process of Chemical Vapour Deposition (CVD) - 

The CVD method is a precise and controlled process that grows diamonds layer by layer from carbon atoms. Here’s how it works:

1. Selecting the Diamond Seed
   A thin slice of diamond—typically 300 microns thick and around 10x10mm in size—is chosen as the foundation. This seed is usually taken from an already lab-created diamond.

2. Cleaning the Diamond Slice
   The seed is meticulously cleaned to remove any impurities. Even the smallest defects can develop into inclusions as the diamond grows.

3. Placing the Diamond in the Chamber
   The cleaned diamond slice is inserted into a sealed CVD reactor chamber, ensuring that no unwanted gases contaminate the process.

4. Flooding the Chamber with Carbon-Rich Gas
   The chamber is filled with carbon-rich gases, such as methane, and heated to extreme temperatures.

5. Optional Nitrogen Addition
   Some producers add nitrogen to accelerate growth, but high-quality diamond manufacturers avoid this, as nitrogen can cause a yellow tint in the final diamond.

6. Diamond Growth Begins
   The gas breaks down under intense heat, and carbon atoms bond to the diamond slice, forming layers that gradually build up over time.

7. Continuous Growth Over Weeks
   Over several weeks, fresh carbon gas continues to enter the chamber, consistently breaking down and depositing more carbon onto the seed, increasing its carat weight.

8. Formation of a Rough Diamond
   The process results in a square, rough lab-grown diamond, which is now ready for cutting and polishing.

Detailed process of High Pressure High Temperature (HPHT) - 

The HPHT method replicates the extreme conditions under which natural diamonds form deep within the Earth. Here’s how the process works:

1. Preparing the Carbon Source
   A small piece of pure carbon—often a tiny existing diamond seed—is placed inside a specially designed containment cube.

2. Applying Extreme Pressure
   The cube is subjected to immense pressure, replicating the natural forces found beneath the Earth’s surface.

3. Intense Heating
   Powerful electric pulses heat the cube to extreme temperatures, further simulating the diamond’s natural formation process.

4. Carbon Crystallization
   Under these intense conditions, the carbon atoms begin to rearrange and crystallize, gradually forming a diamond structure.

5. Formation of a Rough Diamond
   Within a few weeks (typically around a month), a fully developed rough lab-grown diamond is produced.

6. Cutting and Polishing
   The rough diamond is carefully shaped using laser precision and traditional polishing techniques, transforming it into a sparkling, faceted gemstone.

7. Certification & Grading
   The finished diamond undergoes evaluation by reputable grading labs like GIA, where it is assessed based on cut, color, clarity, and carat weight. The certification also verifies that the diamond was created using the HPHT process.

CVD vs. HPHT Diamonds: Key Differences

When comparing CVD (Chemical Vapor Deposition) and HPHT (High Pressure High Temperature) diamonds, the differences primarily lie in quality, aesthetics, and production efficiency.

1. Quality & Aesthetics

• HPHT diamonds are generally regarded as higher quality and more visually appealing.
• CVD diamonds often display brown undertones, spotty inclusions, and internal graining, which can affect their clarity and overall appearance.

2. Production Process

• CVD diamonds are quicker, more cost-effective, and energy-efficient to produce, making them a preferred method for many manufacturers.
• HPHT diamonds require higher energy input and more complex equipment, but the result is typically a purer and more structurally stable diamond.

3. Post-Growth Treatments

• Many CVD diamonds undergo HPHT treatment to remove unwanted brown hues and improve clarity.
• However, this post-growth treatment can sometimes cause the diamond to appear milky or hazy, diminishing its brilliance.

GROWN offers a curated selection of high-quality HPHT-grown diamonds, ensuring exceptional quality and ethical sourcing. 

What Are Lab-Grown Diamonds Made Of?

Pure carbon—just like natural diamonds! Lab-grown diamonds are composed of unaltered carbon atoms, arranged in the same crystalline structure as their mined counterparts. Sometimes referred to as “carbon-made diamonds,” these lab-created gems are chemically, physically, and optically identical to natural diamonds. In fact, their internal structure is so indistinguishable that only specialized equipment can differentiate between the two.