THOSE old plastic bottles and bags that litter Hong Kong's country parks could soon be worth their weight in - diamonds.
A Hong Kong university professor says he can turn ''any waste plastic'' into a thin layer of shining diamond - one of the world's most precious minerals - by simply vaporising it with high-energy laser light.
And the process, being patented, could steal a march on rivals around the world including diamonds giant De Beers, which has spent billions of dollars trying to perfect the technique.
The attraction of diamond is its properties of hardness and heat and electrical conductivity. Films made cheaply in a lab could be used to coat cutting tools and replace industrial diamond stones, or as an insulating layer to keep densely packed microchips from overheating.
Many companies from the United States and Japan are working on vapour deposition of diamond, but the methods involve complicated and expensive equipment to heat methane and hydrogen gas in a vacuum.
Professor Hiroyuki Hiraoka of Hong Kong University of Science and Technology says this is the first time plastic has been used. His system cuts the required temperature by half, to 400 Celsius, and is quicker, cleaner, safer and cheaper than other methods, he says.
A high-energy argon-fluorine laser beam fired at a lump of perspex or polystyrene in a chamber containing reactive hydrogen or methane produces ''fireballs'' of carbon.
