London, Nov 14 : Diamonds are a girl's best friend, but if you don't have enough money to afford one, then here's a piece of information - American scientists have developed a technique that leads to large scale production of cheap, perfect and extra-large 'artificial' diamonds in the lab. The US team has found that microwave cooking can lead to synthetic diamonds, which are far cheaper and cleaner than their natural counterparts.
And to top it all, the improvement also means there is no theoretical limit on the size of diamonds that can be grown in the lab.
Led by Russell Hemley, of the Carnegie Institute of Washington, the researchers made diamonds by chemical vapour deposition (CVD), where carbon atoms in a gas are deposited on a surface to produce diamond crystals.
The CVD process produces rapid diamond growth, but impurities from the gas are absorbed and the diamonds take on a brownish tint.
Usually the scientists go for a costly high-pressure, high-temperature treatment called annealing to remove the defects, but it results in relatively small diamonds.
But, in their research Hamley and colleagues got around the size limit by using microwaves to "cook" their diamonds in a hydrogen plasma at 2200 °C but at low pressure.
So, now the only thing that can limit the size of the diamond is the size of the microwave chamber used. "The most exciting aspect of this new annealing process is the unlimited size of the crystals that can be treated. The breakthrough will allow us to push to kilocarat diamonds of high optical quality," New Scientist quoted Hemley's Carnegie Institute colleague Ho-kwang Mao as saying.
Yufei Meng, who also participated in the experiments, claimed that the new technique is so efficient that the synthetic diamonds contain fewer impurities than those found in nature.
Diamonds, produced as a result of the new method, can immediately be used to make ultra-high quality windows that are optically transparent to lasers.
Artificial diamonds are used in a range of high-end technologies, such as lasers and high-pressure anvils. Some companies have also started to sell synthetic diamonds as gemstones.