Scientists have found a way to grow diamonds from scratch in just 15 minutes.

Scientists have created diamonds at normal air pressure and without using a starting gem. This new method could make it much easier to grow these valuable stones in the lab. 

   

Diamonds are made in the core of Earth, which is the molten zone hundreds of miles below the top of the Earth. Extreme temperatures of over 2,700 degrees Fahrenheit (1,500 degrees Celsius) and pressures of several gigapascals are used in the process.

Conditions similar to those used in this method are used to make 99% of all diamonds that are made in a lab. For high-pressure and high-temperature (HPHT) growth, these harsh conditions are used to turn carbon that is dissolved in liquid metals like iron into a diamond around a small starting diamond. 

The high temperatures and pressures are hard to create and keep up, though. The size of the diamonds is also affected by the parts that go into making them. The biggest diamond is about a cubic centimeter, which is about the size of a blueberry. Also, HPHT makes even these tiny gems in a week or two, which is a pretty long time. Chemical vapor deposition is an alternative method that doesn’t need as many of the things that HPHT does, like high temperatures. But some things don’t go away, like the need for seeds.

Some problems with both of the old ways of synthesizing are fixed by the new method. Rodney Ruoff is a physical chemist who works at the Institute for Basic Science in South Korea. His team released their results in the magazine Nature on April 24. 

The fire for diamonds

It took a long time to come up with the new way. “For over a decade I have been feeling about new ways to produce diamonds, as I thought it might be likely to achieve this in what might be unexpected (per ‘conventional’ thinking) ways,” Ruoff said via email.

In the beginning, scientists cooked gallium and silicon with electricity and put them in a graphite furnace. Gallium might seem like a strange element, but it was chosen because it was shown in a separate study to speed up the process of turning methane into graphene. Graphene is made of pure carbon, just like diamond, but its atoms are arranged in a single layer instead of the tetrahedral pattern found in diamond. 

The crucible was kept in a home-built room that was kept at sea-level air pressure. Superhot, carbon-rich methane gas could be pumped through the chamber. This 2.4-gallon (9-liter) box was designed by co-author Won Kyung Seong, who is also from the Institute for Basic Science. It could be set up for experiments in just 15 minutes, which lets the team quickly do tests with different amounts of metals and gases. 

By making these small changes, the researchers found that a mix of gallium, nickel, iron, and a small amount of silicon worked best to speed up the growth of diamonds. In fact, after only 15 minutes, the team got diamonds from the base of the furnace with this mix. A more full diamond film formed in two and a half hours. Spectroscopic tests showed that this film was mostly pure, but it did have a few silicon atoms in it.

The exact steps that made the diamonds are still not very clear, but the experts believe that a drop in temperature moves carbon from the methane to the middle of the crucible, where it forms a diamond. Also, diamonds can’t form without silicon, which is why the researchers think it might help the carbon organization. 

The new way does, however, come with some problems. On the other hand, the diamonds made this way are very small; the biggest ones are hundreds of thousands of times smaller than the diamonds made with HPHT. They are too little to be used as gems because of this.

It is not clear what other uses the diamonds made with the new method could have, such as in more technological tasks like cutting and cleaning. But Ruoff said that because the process uses low pressure, it could make diamond production much bigger. 

“In around a year or two, the world power has a clearer picture of things like possible retail impact,” he said.

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