How Big Can Lab Grown Diamonds Get?

Table of Contents

  • How Lab Grown Diamonds Are Made
  • Does The Growing Process Affect The Size?
  • Does it Take Longer to Grow Large Diamonds vs Small or Medium-Sized Diamonds?
  • Why Lab Grown Is Optimal For Large Diamonds


When it comes time to choose a diamond, size can play a crucial role. Lab grown diamonds come in all shapes and sizes from small to medium to large. But for those who crave a little something more, how big can a lab grown diamond be?

If you’re drawn to large diamonds, the lab grown process opens the door to endless options. To answer this question, we need to first address the different processes of growing lab diamonds.

Halo engagement ring

How Lab Grown Diamonds Are Made

Within a diamond lab are innovative machines designed for the sole purpose of growing diamonds. The advancement of technology has enabled the process of growing diamonds to exactly replicate the conditions in which mined diamonds form—with one very important exception: lab grown diamonds grow exceedingly fast.

Lab grown diamonds begin their life as a carbon seed. Just like seedlings blossom into flowers in a greenhouse, carbon seeds transform into beautiful diamonds in a lab. Over time, intense conditions like heat and pressure crystallize the carbon into a remarkable diamond.

How long does it take to grow a lab created diamond? Only a few weeks.

Of course, the time it takes to grow a diamond will shape the size of it, but the processes are relatively similar. The result is an extraordinary diamond full of fire, brilliance and scintillation.

Here’s a detailed look at the two main methods for growing lab diamonds:

HPHT Method (High Pressure High Temperature)
The original method for growing diamonds in a lab recreates the same natural conditions required for diamonds to form. To create an environment conducive to growing diamonds relies on using either a belt press, split-sphere press or cubic press. All of these mechanical presses are large enough to apply two elements:

  • Extreme pressure
  • High temperature

The mechanical press employs these two conditions to form a diamond seed from carbon. With the introduction of extreme heat (roughly 2000°F) and around 1.5 million pounds of pressure per square inch, a distinct crystal structure begins to form.

This precise and controlled environment enables the seed to perform as the foundation upon which carbon lattice grows. During the growth process, crystal layers compound and the carbon melts away. Finally, the diamond seed is cooled into a crystal carbon structure.

While this process creates an environment perfect for diamond production, the more commercially used method is Chemical Vapor Deposition (CVD).

Accented engagement ring CVD Method
CVD is similar to HPHT in that it uses a portion of a diamond seed to grow a diamond. However, it departs in the elements used. Whereas HPHT relies on extreme heat and pressure, CVD uses vapor gas, heat and low pressure.

First, a portion of the diamond seed is put into a CVD reactor. Then at very low pressure, a mixture of carbon gas vapors fill the chamber, and microwaves ionize the gases into plasma. Once the temperatures within the chamber are extremely high, the ionized plasma breaks down the gas molecules and allows carbon to bond to the diamond seed. Within a short time frame, layers of crystal form into crystal carbon.

While the processes differ, the result is the same product: a striking lab grown diamond.

Cushion cut engagement ring

Does The Growing Process Affect The Size?

The most commonly used process to grow diamonds is HPHT, as it’s been around the longest. Yet CVD is rapidly emerging to the forefront of the industry. In terms of size, HPHT has proven capable of growing very large diamonds, with sizes reaching over 10 carats.

Yet the landscape for lab grown diamond technology is ever-growing and fiercely competitive.
In recent years, CVD has closed the gap between HPHT by increasing its production size capability from 6-carats to over 9-carats. In fact, the largest lab grown diamond in the world is a whopping 155-carat disc diamond, grown via CVD.

With this fact in mind, is there a preferred process for growing large diamonds?

This is where HPHT has a slight edge over CVD. How big is that edge? Referring back to the averages of jewelry grade lab grown diamonds, HPHT can grow diamonds to a size exceeding 10-carats. Comparatively, CVD is not far behind with the capability of growing 9-carat diamonds.

Considering these figures, it’s difficult to pinpoint one process over the other as they are both effective methods for growing large diamonds. While the two processes differ, the size possibilities seem to only be growing with advancements in technology.

This means there is essentially no cap on how big lab grown diamonds can get. As a consumer, this comes as incredible news because ultimately, you have the choice to select any size you like for your lab grown diamond.

All in all, the size of a lab grown diamond is shaped by the time it takes to grow it.

Accented halo engagement ring

Does it Take Longer to Grow Large Diamonds vs Small or Medium-Sized Diamonds?

In general, it takes a mere few weeks to grow a diamond in a lab, compared to the millions of years it takes diamonds to form in the earth. Of course, the specific growing technique used also influences the time frame.

HPHT uses extreme pressure to carefully grow a diamond. As the diamond grows in size, the pressure must alter to maintain control over the growing process. To visualize this concept, imagine trying to squeeze a small pebble. Not too difficult, right? Well, now imagine that pebble transformed into a large rock. Would you still be able to squeeze it with the same amount of pressure, or would you have to apply more pressure with the assistance of an extra hand?

Growing a diamond to a large size is a methodical process. Fortunately, a lab is the perfect environment to accommodate the process. While relatively small to medium diamonds can form within only a couple weeks, large diamonds require more time and finesse.

Still, it’s absolutely possible and opens up a world of options when it comes to choosing the size of your lab grown diamond.

Solitaire engagement ring

Why Lab Grown Is Optimal For Large Diamonds

Lab grown diamonds are recommended for large diamond sizes because they are meticulously grown without compromise to quality or brilliance.

Are your sights set on a striking large diamond? Then lab grown diamonds are the premium choice.

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