Which type of Lab-Grown Diamond should you choose for Engagement Ring?

Not all Lab-Grown Diamonds are created equally

Lab-Grown Diamonds are fast becoming a prestigious and recognisable alternative to natural mined diamonds. These remarkable stones which offer the same physical and visual characteristics as their natural diamond counterparts fall into two distinct categories based on the methods through their creation, HPHT or CVD.

It may be an entirely new concept to learn that not all Lab-Grown Diamonds are created equally. However similar they may sound, HPHT and CVD couldn’t be more different when it comes to their processes. They are polar opposites in the way in which they are produced.

It’s often a fierce debate as to whether CVD or HPHT are the best option for lab-grown diamonds. One type is the golden standard, whilst the other is outdated, expensive and unsustainable. There is not only a lot of confusion with clients, but also a great divide in the Lab-Grown Diamond world.

The two methods to create a Lab-Grown Diamond are called HPHT (High Pressure High Temperature) Lab-grown diamonds and CVD (Chemical Vapor Deposition) Lab-Grown diamonds. These two methods are significantly different - one mimics the natural heats and pressures deep within the earth (HPHT), whilst the other mimics how diamonds are formed in interstellar clouds (CVD). These two very distinct processes bear a huge influence on the diamond’s characteristics and overall quality.

In this comparison we will explain the two processes of creating lab-grown diamonds, HPHT (high pressure high temperature) and CVD (chemical vapor deposition) and highlight the differences to explain what sets them apart. Everything between the catalyst (seed to grow a diamond), the chambers they grow within, the technologies and the amount of resources they use, and of course the finished lab-created diamond.

The Process: How each Lab-Grown diamond is formed

CVD (Chemical Vapor Deposition)

CVD (Chemical Vapor Deposition) is the newest method of growing lab-grown diamonds. A CVD Lab-Grown Diamond is derived from a real diamond seed. A fragment or slice of a Type IIA diamond is placed within a vacuum chamber as carbon is gradually added. The sealed chambers are then heated to between 700-1300 degrees celsius. The purest carbon atoms attach to the diamond seed and grow slowly layer by layer and a diamond rough starts to grow. This process continues for between 4-8 weeks as the CVD Diamond rough forms into a cubic shape. The CVD diamond rough shows no unnatural growth patterns or markings, with an interior structure most similar to natural diamonds.  This produces CVD Lab-grown diamond roughs - the closest thing to a natural diamond.

HPHT (High Pressure High Temperature)

HPHT (High Pressure High Temperature) is the original method of producing lab-grown diamonds. A HPHT diamond begins with a graphite metal seed that is carefully placed within a specially designed HPHT chamber. The chamber press is then heated as high as 1300-1600 degrees celsius where the graphite seed is placed under a tremendous amount of pressure. Carbon atoms within the HPHT chamber will crystalise and gradually attach to the seed in all directions. This process takes place for 4-12 weeks to grow, finishing with a diamond rough in an octahedral shape. HPHT diamond roughs show many internal growth patterns that can include metallic and dark inclusions, colour zoning (uneven colour throughout) and strong grain patterns within. 

DNA of the Diamond - Where Lab-Grown Diamonds begin (the seed)

CVD (Chemical Vapor Deposition)

CVD Lab-Grown diamonds derive from the most premium diamonds, a Type IIA diamond. Type IIA diamonds account for only 1-2% of all mined natural diamonds in the world. Type IIA diamonds are coveted as they have no nitrogen impurities within the stone, rarely contain imperfections and exhibit high grades of colour. A small slice or fragment of these real Type IIA diamonds are used as diamond seeds for CVD Lab-grown roughs. To begin the CVD lab-grown process, they are arranged carefully within their vacuum chamber as the catalyst of a diamond rough to grow. A CVD diamond will always be the whitest and brightest lab-grown as it has perfect DNA of a Type IIA diamond. CVD Type IIA lab-grown diamonds will offer the highest quality and consistency to be the closest to a natural diamond.

HPHT (High Pressure High Temperature)

HPHT diamonds are derived from a HPHT seed and the addition of a molten metal flux (the mixture of three metals containing iron, nickel and cobalt).  These make up the catalyst which initiates the lab diamond growth process. The carbon starting material of graphite is the source of a HPHT diamond. The downside to the exposure to metals during the formation is that HPHT Diamonds is that they will exhibit metallic inclusions. These are part of what identifies a HPHT lab-grown when gemologists test a stone. If a diamond is magnetic and exhibits grain growth patterns in many directions it will likely be categorised as a HPHT lab-grown.

The Resources and Efficiency - What it takes to create a lab-diamond

CVD (Chemical Vapor Deposition)

CVD lab-created diamonds are considered far more energy efficient when compared to the HPHT process, making them the greener option in terms of energy consumption. CVD diamonds require far less heat and pressure to produce as they form at lower temperatures within smaller chambers. Therefore their production requires less energy and smaller facilities. The CVD Lab-Grown process also offers superior control over the growth process. The controlled environment results in more consistent and predictable outcomes to ensure desirable diamonds that achieve a certain carat weight and quality. The end result of the CVD process is one which creates lab-diamonds with less waste, less emissions and less resource consumption.

HPHT (High Pressure High Temperature)

The method to create HPHT lab-diamonds is very costly and energy consuming. To replicate the natural conditions of diamond formation deep within the earth at extreme pressures and temperatures uses a tremendous amount of resources. There is not only the consideration of the exorbitant energy usage to power the large HPHT chambers, but also the large scale of the locations. These purpose-built industrial facilities are colossal in size to support the enormous weight and size of the equipment required.

There are also many challenges in maintaining consistent conditions using the HPHT diamond growth process, meaning the finished diamond roughs exhibit a greater variability. This means the desired diamond characteristics can be more difficult to achieve. Because of this, HPHT hasn’t always had the best reputation in terms of sustainability. The process can produce a lot of wastage (many HPHT diamonds are discoloured or heavily included) meaning many are destined for commercial use for industry (diamond cutters, machinery etc) instead of fine jewellery.

The Quality - finished Lab-Grown Diamonds

The CVD process creates chemically pure diamonds that achieve the highest colour and clarity. A CVD Type IIA Lab-Grown diamond will exhibit the most even colour distribution and sparkle the whitest and brightest. Much of this can be attributed to the revolutionary technologies and their purity (the best quality diamond seed in which they originate from). A CVD diamond is closest in characteristics to a natural diamond.

HPHT diamonds are often magnetic with metallic inclusions from the graphite and catalyst molton metals used to form them. About 85% of HPHT stones will be magnetic due to these impurities. HPHT lab-grown diamonds can contain traces of Boron and Nitrogen or other undesirable particles within the stone. These impurities give the appearance of yellow, brown or blue hues. HPHT Diamonds often require heavy treatments to improve their colour and clarity. They are often placed under further heat treatments to optimise the stones, to enhance their colour to acceptable grades and alter them into diamonds fit for jewellery. 

CVD or HPHT lab-grown diamonds, which should you choose?

Within the industry experts are unable to tell the difference between a natural and a lab-grown diamond without Gemological Testing. Lab-grown variations produce diamonds that are chemically and visually identical to natural diamonds. The differences are unveiled through the processes and the quality of the finished diamonds they produce. Each lab-grown diamond is assessed under the same diamond grading system to establish their quality and determine the 4C’s.

In terms of superior lab-grown diamonds. There is one clear winner: CVD Lab-Grown Diamonds.

Combined with the latest technology they reign supreme in the world of Lab-Grown diamonds. CVD diamonds are less labour intensive, more sustainable for the environment using less energy and resources and consistently produce better quality diamonds. CVD Lab-Grown diamonds have the best reputation in the industry. With DNA from a perfect Type IIA diamond, a CVD Lab-Grown is a diamond dream. There are a few things that the CVD Lab-Grown diamond process just does better.

See more: Lab Grown Diamond vs Natural Diamond

At JANAI, our diamond specialists will guide you to find the best diamond. We offer the largest range of lab-grown diamonds for your to choose from for your custom engagement ring in Melbourne. Fill out the form to request your booking with us below.