How are Lab Grown Diamonds made?

Lab-grown diamonds are made by mimicking the same conditions below ground which create natural diamonds but in a laboratory setting. The main difference is that while natural diamonds take billions of years to form and pre-date the dinosaurs as one of the oldest minerals on the planet, the controlled conditions of lab grown diamonds can be created in a much shorter time frame. 

There are two main methods used to create lab-grown diamonds. The first and most commonly used is through a high-pressure, high-temperature treatment, which subjects a carbon source to intense pressure and heat to create a diamond. The other method, known as Chemical Vapour Deposition (CVD) breaks down carbon-rich gas which allows carbon atoms to deposit onto an existing diamond seed and grow into a beautiful diamond.  

In this guide we’ll explain, step-by-step, how these methods are used to create lab-grown diamonds.

How are High Pressure High Temperature (HPHT) Diamonds Made? 

Step 1: Carbon Source

A small piece of pure carbon, (usually graphite) is selected to form the foundation of the lab-grown diamond. 

Step 2: High Pressure and High-Temperature Treatment

A cubic press and heating chamber are used to recreate the same conditions under the earth's crust. The equipment applies:

At least 5 gigapascals of pressure (the same level of pressure present 500 km below the Earth’s surface) 

AND

1,300C of heat (hotter than lava from a volcano!)

Step 3: Crystallisation

The extreme heat and pressure generate enough energy to melt the carbon source and cause it to crystallise. These crystallised carbon atoms grow layer by layer in a diamond cubic structure.

Step 4: Stabilisation 

Once the crystal layers are formed the chamber is slowly brought back down to room temperature, allowing the diamond to slowly stabilise and solidify. While this process takes over a billion years in nature, the whole process takes just a few days for a smaller diamond and weeks for a larger diamond in a laboratory. 

Step 5: Diamond Treatment

Once the diamond is fully formed, it's removed from the press and heating chamber and is treated if needed. It’s polished, then cut into its most appropriate diamond shape to ensure it holds the largest carat weight possible for that batch, it is then graded and certified and ready to go to market.  

How are Chemical Vapour Deposition (CVD) diamonds made?  

Step 1: Diamond Seed

A thin slice of diamond, only 300 microns thick, known as a diamond seed is used to create a CVD diamond, it’s placed in a vacuum chamber.

Step 2: Gas Exposure  

The vacuum chamber is then pumped with a carbon-rich gas such as methane, to expose the diamond seed to carbon molecules. 

Step 3: Heating

The methane gas in the chamber is heated between 700-1200C, which is more than twice the temperature of the surface of Mercury. The high heat creates plasma which breaks down the gas molecules to release pure carbon atoms.

Step 4: Crystallisation

Once the carbon molecules are released, they begin to settle onto the diamond seed, building the diamond layer by layer, and bonding with the existing material. This process continues for weeks until the diamond reaches the desired side. 

Step 5: Diamond Treatment

Once the diamond is fully formed, it will need polishing and treatment to remove any browning caused by the CVD process. After this, it is cut and polished ready to be graded and certified.

How to choose a Lab Grown Diamond

Lab-grown diamonds have the same chemical properties as natural diamonds and are identical to look at from every angle. The main difference of choosing a lab-grown diamond is that it takes less time to produce and cuts out the need to be mined or transported, which is a benefit as it then costs less to produce and in turn less to buy compared with natural diamonds. Meaning when you choose a lab-grown diamond you’ll be paying less than you would for a natural diamond of the same quality.

Choosing a lab grown diamond follows the same consideration as a natural diamond would. 

• Budget: Consider how much you want to spend on your lab-grown diamond. Remember we can also offer 12 months finance for orders over £560. 
• Cut: The cut of the diamond impacts the diamond's overall brilliance and shine. The better quality cut, the more the sparkle and the more your diamond will be valued at. 
• Clarity: Despite being created in a lab, inclusions, or flaws, can still be present in a lab-grown diamond. Flawless diamonds are the most valuable. However, diamonds with a clarity of VS1 and above will appear clear to the naked eye. 
• Carat: The carat is the weight of the diamond, the physical size of the diamond can vary depending on the cut of the diamond.
• Colour: Lab grown diamonds can be heat treated to improve the colour grade, a completely colourless diamond will be the most expensive, whereas near colourless and lower colour grades are beautiful diamonds and more affordable.

Looking for high-quality lab-grown diamonds? Well, here at Diamond Heaven, we’ve got you covered. Our expert team of diamond experts can help you choose the perfect diamond for any occasion. Simply book an appointment today or visit us in-store.