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HOW ARE LAB GROWN DIAMONDS MADE?

 

The ultimate dream of creating a beautiful, scintillating, and valuable diamond from a simple carbon atom has long captivated the mind of scientists and visionaries for many generations. Just like how the alchemist turned lead into gold, many have attempted this seemingly impossible feat. However, only recently in our lifetime, we are able to produce gem-quality, lab grown diamonds that are large and beautiful enough to be used in jewellery. What did we go through to get here?

Henri Moissan attempting to make diamonds over 100 years ago. Picture Source: https://www.loc.gov/resource/ggbain.02112/  

 

Many have tried to synthesize jewellery grade diamond, however the first documented attempt was by Henri Moissan. In 1893, he claimed to have successfully grown a diamond by heating charcoal to 3,500 degrees Celsius inside a carbon crucible. Numerous attempts were made afterwards; some reported successes, however, mostly were unverified.

Diamond is essentially a crystalline form of carbon, arranged in a tetrahedral arrangement regardless of their source (mined or lab grown diamond). For many years, manufacturers have tried to grow diamonds like how they grew rubies, sapphires, emeralds and other precious gems, however, most have failed. Until they tried to recreate the same environment in which diamonds grow in nature.

 

 

METHOD 1: HIGH PRESSURE HIGH TEMPERATURE DIAMONDS (HPHT)

In nature, a diamond is formed from carbon to crystals in very deep underground. Typically, diamonds grow naturally at about 100 miles below earth’s surface. It needs to have a condition of extreme high pressure and high temperature to form. The diamond that we can find closer to the earth’s surface typically is a result of volcano eruption which brought the stones nearer to the earth surface where human can mine them.

Picture Source: “Populyarnaya Mekhanika

Not surprisingly, the first method that has successfully created lab grown diamonds is made by recreating nature’s way of creating a diamond with High Pressure High Temperature manufacturing

There are three main manufacturing processes used to make HPHT diamonds: the belt press, the cubic press and the split-sphere (BARS) press. The purpose of each process is to recreate an environment of extremely high pressure and temperature where diamond growth can occur. Similar to growing a plant, each process starts with a small diamond seed (a thin sheet of diamond) placed in a carbon chamber and put under high pressure and temperature. Over time the carbon in the chamber will deposit on the diamond seed and create a larger diamond.

 

The General Electric invention of the belt press requires an upper and lower anvil to generate pressure of over 1.5 million pounds per square inch and temperature of above 2,000 degrees Celsius. In such an environment, the pure carbon will melt and begin to form into a diamond on the starter seed.

On December 16, 1954, a belt press was used to create the first man-made lab grown diamond. The diamond was very small and nothing like the ones we use in jewellery currently. In fact, until today, most of the lab grown diamonds are not of jewellery quality. Instead, they are made for industrial applications. Given that 1 of a diamond’s quality is that it is  of the hardest materials with a very impressive thermal conductivity, they are the material of choice for cutting tools and semiconductors.

Since the first success of growing lab grown diamonds, belt press designs have been dramatically scaled up, more modern cubic and split-sphere presses have been used which are more efficient, and larger, more perfect gems are being produced. 

As of today, the largest gem quality, faceted, lab grown diamond has been produced by NDT using the HPHT method with a cubic press. Weighing in at 10.02 carats, this incredible diamond is graded as E color and VS1 clarity.

METHOD 2: CHEMICAL VAPOUR DEPOSITION (CVD)

Chemical Vapor Deposition (CVD) is a more recently developed technique to grow a diamond using hydrocarbon gas mixture. Similar to HPHT process, CVD process also uses a thin slice of diamond seed which is then placed in a sealed chamber and then heated to around 800 degrees Celsius. The chamber then filled with a hydrocarbon gas which are then ionized into plasma using microwaves, laser or other methods. The ionization intention is to break the molecular bonds in the gases and pure carbon will then adhere to the diamond seed and slowly build up into a larger crystal, atom by atom, layer by layer.

 

The CVD process has some advantages over HPHT. Apart from the less pressure and temperature needed, CVD process often uses hydrocarbon gas such as methane gas which is often deemed as a greenhouse gas. 

Indirectly,  it helps to reduce greenhouse gases by turning it into a diamond. CVD diamonds can be grown over larger areas by starting with a larger diamond seed plate as the high pressure does not need to be concentrated over a small surface area. Finally, the CVD process allows for a more accurate control over the environment in the growth chamber and hence the property of the finished diamond can be more controlled. However, similar to growing plants, no 2 diamonds have the same characteristics and all diamonds have a character of their own. 

Given all of these advantages stated earlier, the largest known polished CVD diamond in the world is only a 3.23ct, and it was graded I color and VS 2 clarity.

That said, given the amount of greenhouse gases emissions going on in space, the technology has been improving at an unprecedented rate. Only time will tell when the CVD method-produced diamonds reach the same quality of HPHT diamonds.

SO SHOULD I CHOOSE CVD OR HPHT DIAMOND?

After explaining the different methods above and listing pros and cons of each method, fortunately, there are no material differences between the two from a consumer perspective. Similar to natural diamond, the beauty of a lab grown diamond comes from its physical characteristics and not the specific method by which it was grown. However, it is crucial to get a properly graded lab grown diamond from a trustworthy jeweller with their own quality control checks. You wouldn’t want to have a diamond with subpar light performance.

 

WHERE CAN I BUY A LAB GROWN DIAMOND JEWELLERY IN SINGAPORE?

Same as mined diamonds, the 4Cs are used to assess lab grown diamonds in Singapore and certified by 2 world-renowned gemological institutes, GIA (Gemological Institute of America – https://www.gia.edu/) or IGI (International Gemological Institute – https://www.igi.org/) . The diamond’s certification and grading will dictate the quality of the lab grown diamond that you are looking to purchase in Singapore. At Authica Jewellery, we are proud to say that we are one of the pioneers who brought GIA certified lab grown diamonds to sunny Singapore.

At Authica Jewellery, all our lab grown diamonds went through a strict quality control beyond the 4Cs or just simple triple excellent quality which is often used by many other jewellers in Singapore. We have devised a cut quality check that is stricter than GIA’s excellent (best cut) and IGI’s ideal (best cut) possible. This is to ensure that our lab grown diamonds will have optimal light performance in all lighting conditions – no matter rain or shine so to say. 

Thus, rest assured that every single diamond jewellery that has been sold by Authica to you are of AA (Authica Approved) quality!

Team AJ (Team Authica Jewellery) is more than happy to share with you our passion for lab grown diamonds and our strict quality control process. Find us at https://authica-j.com/ or set up an mini diamond advisory session with us at https://authica-j.com/find-us/

We look forward to welcoming you to our Authica studio soon!