Synthetic Diamonds

Man is the most evolved being of this planet. What sets a human apart from other living beings is that he has the most advanced mental capabilities. This has provided man with the ability to discern, comprehend and most importantly it triggers inquisitiveness. Curiosity is what has led to many important inventions and discoveries in the history of mankind. Man has observed the way nature works and tried to imitate the same. One of the finest example of this is synthetic diamonds, where in scientists have tried to reproduce the same extreme conditions in a laboratory, which exist in the core of the earth for diamond formation.

Synthetic diamonds are also known  as “cultured/lab-grown” diamonds. They can be defined as man-made diamonds which ape a natural diamonds physical, chemical, thermal and electrical properties and essentially have the same chemical composition.

In the early 1950’s the General Electrical scientists were trying to create synthetic diamonds with High Pressure High Temperature(HPHT) methodology. Diamond and graphite are both forms of carbon but, the stronger bond of the carbon atoms in diamond is what gives it its prized form. The biggest challenge that stood in front of scientists was how to convert graphite into diamond. Experiments were carried out for years wherein graphite was subjected to intense heat and pressure but it was all in vain. Until they discovered that in a meteorite crater in Arizona, diamonds were found in a substance called troilite. This is what gave them a break through. In the year 1956, they had succeeded in their experiment where they put together troilite and graphite and then exposed them to immense pressure and temperature.

HPHT DIAMOND PRESS

HPHT DIAMOND SYNTHESIS

Major advancements have come about in this technology of manufacturing synthetic diamonds. Mainly now synthesis takes place with the help of  a diamond seed crystal. Graphite along with catalyzers are placed in huge diamond presses. The chemical reaction which take place under high heat and pressure result in crystallisation of diamond. This technique is now most importantly used for enhancing the color of natural diamonds. Usually diamonds are divided into two categories – Type 1 and Type 2 depending on the kind of impurity they have and these are subdivided into two categories each.

Type 1 diamonds are abundant in nature and mostly contain nitrogen. These diamonds are usually colorless, yellow or brownish. Whereas, Type 2 diamonds are rare and contain little or no nitrogen or boron.

TYPE	IMPURITY	COMMON COLORS
Type 1 A	Nitrogen – plentiful	Colorless, yellow
Type 1 B	Nitrogen – less	More yellow
Type 2 A	Nitrogen – little/no nitrogen	Colorless, brown or grey
Type 2 B	Nitrogen – little /no nitrogen/ boron	Blue

The HPHT treatment is mostly carried out on Type 2A diamonds to convert  them from brown to colorless diamonds. Type 1A diamonds are treated to produce green, yellow and orange colors.

Another method which was synthesising diamonds in the early 1950’s was Chemical Vapour Deposition commonly known as CVD. This process uses thin diamond chips as a seed on which the diamond crystals grow. Crystallisation takes place when methane and hydrogen are subjected to low pressure and heat in a vaccum chamber. Heat and pressure break down hydrogen molecules into single atoms (atomic hydrogen). This hydrogen reacts with methane. This reaction results in formation of pure carbon which starts attaching itself to the seed crystal and as more and more carbon atoms attach themselves the diamond crystals grow.

 

DIAMOND SEED CRYSTALS

CVD GROWN DIAMONDS

CVD VACCUM CHAMBER

Earlier  the use of synthesised diamonds was limited to industrial purposes wherein diamond cutting tools and various other equipments were made. But now, the application of synthetic diamonds is not only limited to gems and jewelry industry.  Due to its excellent thermal, electrical, physical and optical properties it has stretched its wing over various other sectors such as health care and electronics industry.

Certain companies are producing excellent quality synthetic diamonds. Among the top producers are Gemesis, Chatham and Scio Diamond Technology Corporation  which are American companies. AOTC – Advanced Optical Technologies Corporation from Netherlands.

Synthetic diamonds have revolutionised the market and they are affordable and within the reach of masses. Along with it consumers who are concerned about blood diamonds, it also gives them an opportunity to wear responsibly created diamonds. Synthetic diamond is an excellent invention of the ever inquisitive human being, except for the challenge that it has posed in front of the natural diamond industry.

*The Author is a Colored Stone Graduate from Gemological Institute of America, Mumbai and a Diamond Graduate from Solitaire Diamond Institute, Bangalore. She also holds a Diploma in Jewelry Designing & Manufacturing from Jewelry Product Development Centre, Jaipur. She also blogs at 'The Jewel Affair'.

*Picture Courtesy: Google Images