Science Video

Man Made Diamonds
Materials Scientists Make Valentine Treats Affordable

February 1, 2007 — New and improved technology has now made growing diamonds cost-competitive with mining them. Diamond-making machines subject a graphite-carbon core and a diamond seed at a pressure of 850,000 PSI for four days, recreating conditions similar to those 100 miles below the earth's surface. The lab-grown diamonds that come out are optically, chemically and physically identical to those that occur in nature.

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Diamonds. They're the symbol of love ... Romance and weddings. But you don't have to get a little blue Tiffany & Co. box to get one. A small white box is the key to making a diamond. It's in machines in Sarasota, Fla., where real diamonds are grown by man.

Clark McEwen, chief operating officer of Gemesis Corp., oversees it all.

"Basically what we do here is we recreate, or emulate, the process that occurs 100 miles below the earth's surface," McEwen tells DBIS.

A core made of graphite, carbon and a diamond seed is strategically placed in the middle of what is essentially a very large pressure cooker. "It's like putting together a large heavy puzzle," Gemesis "Senior Diamond Growth Technician" Chris Owens tells DBIS. "Each one of these anvils weighs about 30 pounds."

Graphite and diamonds are both made from pure carbon atoms. Under extreme heat and pressure, carbon atoms attach themselves to the seed, forming a diamond crystal. McEwen says, "There's about 500 different variables in the process, and if any one of those variables is slightly off, we get a different outcome."

The machine reaches 1,500 degrees, and the pressure on the core is 850,000 pounds per square inch -- that's equivalent to 100 8,000-pound elephants standing on a coin. Once the machine is closed, nature takes over. Four days later a very crushed core is taken out, and a man-made diamond is inside.

"Structurally they're, they're identical. Optically, chemically and physically they're identical to a mine diamond," McEwen says. Gemesis makes yellow- and orange-colored diamonds because fancy colors are in demand.

But diamond-making is not an exact science. Some turn out beautiful. Others, not so good.

McEwen says there is a misconception that every one of the man-made diamonds is perfect. That's not the case. "Just like in nature, each one of these grows individually and has its own unique characteristics," he says. The rough diamonds are then graded and sent out to be made into what many women want for Valentine's Day.

Just to give you an idea on the cost, a one-carat yellow diamond from nature costs about $20,000 and a man-made one costs about $6,000. Also, The Gemesis Corporation has its name inscripted on all of its diamonds so consumers know they are man-made.

BACKGROUND: The growing availability of cultured "man-made" diamonds to consumers is helping to bring down the overall cost of the gems, especially colored versions, such as yellow diamonds, which rarely occur in nature. For example, Gemesis now makes cultured diamonds that are nearly identical to natural stones; the differences can only be distinguished by using cutting-edge laboratory equipment.

ABOUT DIAMOND: Diamond is a crystalline form of pure carbon that forms under intense heat and pressure -- conditions found in volcanic pipes, for example, or when meteors strike the earth can create shock zones of high pressure and temperature. Diamond is the hardest known naturally occurring material, which is why it is popular for cutting and grinding tools, such as diamond-tipped drill bits or saws. Cultured diamonds are formed in the same way as natural mined gems, except they are created in a heavy steel chamber about the size of a washing machine. Lumps of carbon/coal are placed in a globe-shaped chamber, which is then sealed before raising the internal heat and pressure to the same conditions required to compress diamond.

MELTING DIAMOND: Scientists at Sandia National Laboratories use strong acoustic shock waves to melt diamond. Diamond is one of the toughest substances known, but when it encounters acoustic shock waves with strengths between 6 and 10 Megabars, the result is a mixture of molten carbon and solid diamond. Melting diamond completely requires shock waves stronger than 10 million times earth's atmospheric pressure. The shock wave transfers large amounts of energy to the diamond material when it strikes, increasing not just the pressure, but also the temperature. If the shock wave is powerful enough, the temperature will get so high, the diamond will begin to melt into liquid carbon.

The Materials Research Society contributed to the information contained in the video portion of this report.

Note: This story and accompanying video were originally produced for the American Institute of Physics series Discoveries and Breakthroughs in Science by Ivanhoe Broadcast News and are protected by copyright law. All rights reserved.