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 TV portion of this report.