Lab-grown diamonds can be considered a type of magic.
No really, if you were to think about it, we are pretty much-creating diamonds out of thin air. What was once something that seemed like complete fiction has now become a reality. However, Lab-created diamonds should not be surprising to you at all. They have been around for decades already.
There have been strong debates on whether or not it is better to go with natural diamonds or synthetic. Some people even have very strong views about the value and ethics of creating a lab diamond and question the moral choice of going for something lab-created for a custom diamond engagement ring.
Nowadays, we have begun to encourage the industry of lab-made diamonds because of their various benefits for the environment. Natural diamond mining involves the digging of holes so large that they can supposedly be seen even from outer space.
These synthetic diamonds are still considered “real” too; as they are made up of the exact same chemical composition and physical properties as a natural diamond. Even expert gemologists cannot tell the difference with the naked eye. To date, there are currently four different methods of creating man-made diamonds:
- High-Pressure High Temperature (HPHT)
- Chemical Vapour Deposition (CDV)
- Detonation of Explosives
- Ultrasound Cavitation
This article is going to explain how each of these processes works, without it sounding like you are getting a lecture from Albert Einstein.
High-Pressure High Temperature
HPHT is the first method discovered to create a man-made diamond. Introduced in the 1950s, the process is pretty self-explanatory because of its name.
It uses high pressure and high temperature inside a press design to create a diamond. It is closely related to the process of how natural diamonds are created, because of the high pressure and temperatures of our deep Earth.
Natural diamonds are formed when carbon deposits deep in the earth are exposed to very high pressure and temperatures. Certain stones can get their shape in a few months or even days – others take years to materialise. We are talking millions of years too.
With natural diamonds, that is usually the case. It is actually almost impossible to tell how old a natural diamond is. Most diamonds formed deep in the earth are millions or billions of years old. The process of a natural diamond formation can involve various different things too.
Sometimes, a diamond that is being formed naturally can be interrupted and has to wait years for the conditions to be suitable again.
HPHT tries to replicate the process of a natural diamond formation.
There are three main press configurations too. The most common is a belt press, in which two anvils push extreme force from the top and the bottom onto a belt of pressed steel bands, while at the same time zapping electricity through the steel.
Other press configurations include the split-sphere press and the cubic press.
A “diamond seed” is then placed at the bottom of the press. A diamond seed is a single crystal diamond in a slice about the width of a strand of human hair.
The press is heated above 1400 degrees Celsius and then melts the solvent metal. Then, the molten metal eats away at the carbon source – transporting it into small diamond seeds and precipitates. This then will later form into a large lab-grown diamond.
With a natural diamond, it tends to form around the shape of an octahedron – meaning it has eight faces. You will find that HPHT made diamonds will have cubic shapes and eight-faced shapes like natural diamonds.
The shapes of man-made HPHT and natural diamonds are different, meaning that the growth patterns internally for them will be very different too. Growth patterns for the diamonds are one of the only proper ways in being able to tell the difference between natural and synthetic diamonds.
Chemical Vapour Deposition
This process is also used for other manufacturing purposes, not just for creating diamonds. CPV is used to produce high grade, top performance solid materials. The process is often used in the semiconductor industry.
The process has been around since the 1980s and has been the subject of intensive worldwide research. The cool thing about CVD diamonds and why it is so close in competition to the original HPHT method is that it has the power to form diamonds over bigger areas and on all sorts of types of materials.
The precise control over the impurities makes a better quality diamond. The CVD process does not require as high pressures.
Firstly, a small disc that has around 15 to 30 diamond seeds gets put in a “diamond growth chamber”. A “plasma” ball of immensely heated gases is then released into the chamber. The temperature is then heated to around 900 to 1200 degrees celsius. This level of heat creates an ideal gem.
The gases then stick to the diamond seed, which then grows atom by atom for around three to four weeks. This is then likely to be used by an engagement ring designer.
Computers check up on the growth rate of the seeds and stop at the perfect time to maximise the diamond’s properties. Afterwards, the rough diamonds are taken out to be cut and polished.
Detonation Diamonds
Extremely tiny diamond crystals (we’re talking nanometers here) can be made by exploding carbon-containing explosives in a metal chamber – this is where we get the name “detonation nanodiamonds”.
When the explosion occurs the unbelievable amount of pressure and heat in the metal becomes so powerful that they start to convert the carbon of the explosives into diamonds. The chamber gets put in water which takes the heat away quickly after the explosion.
In another method of creating detonation diamonds, a tube made of metal is filled with graphite powder (the stuff used to make pencils). The detonation heats and pushes the graphite to such an extent that it gets converted into a diamond.
The result is usually high in graphite and other unrelated materials, so it needs to be put in boiling hot nitric acid for 24 hours at 250 degrees celsius to dissolve.
Ultrasound Cavitation
This method is far less popular compared to the others.
Like detonation diamonds, ultrasound cavitation (or Ultrasonic Synthesis) creates very tiny diamonds. Graphite again is used, this time in a liquid at room temperature and a liquid at atmospheric pressure and with ultrasonic cavitation – they create these micron-sized diamonds.
Ultrasonic cavitation means that sound waves from a machine are used to synthesise a diamond. These sound waves have frequencies above the upper limit of human hearing.
The yield from this method is about 10 per cent of the weight of the graphite that was used. The cost produced by this technique is similar to HPHT. The quality of the crystals is definitely worse for the ultrasonic process. The ultrasonic method only needs fairly simple equipment, but it has only really been documented by just two groups under research. Currently, there isn’t any proper industrial use.
Conclusion
Although there are four methods for creating a synthetic diamond, HPHT and CVD are the most common.
The CVD method looks like it will begin to overtake the HPHT method in the coming years, and perhaps ultrasonic cavitation will begin to improve and become more efficient.
There are also many reasons to want to buy lab-grown diamonds too. Whatever your choice, diamonds are forever going to be the world’s most prized gem.
by Australian Diamond Brokers : August 22nd 2022 Come visit our store or browse our website to find out more.