The technique has baffled and excited scientists. Diamond is a remarkable material, whose qualities are most useful if it can be laid down in thin layers. But the search for a cheap, reliable way to do this has perplexed experts for years.
Many of those attending today's meeting have spent millions of pounds seeking solutions, yet found none as elegant as Mr Nagy's. Some now believe his approach could revolutionise whole industrial sectors. Consistent, tough, non-corrosive diamond films could find application in markets ranging from missiles and medical appliances to kitchen pots and computer chips.
Several big companies, wary of being identified, have already produced ideas such as coating building materials to create anti- graffiti surfaces, long-lasting guillotine blades for printing presses and tough, smooth diamond-coated razor blades.
Others find the discovery hard to believe. The most cynical, with investment in more expensive - but established - methods, hope this cheaper approach will fail.
Mr Nagy, of East Sheen, south-west London, who has no formal qualifications, stumbled on his process a few years ago when investigating Teflon coatings. His prototype machine consists of a 'mop' impregnated with diamond dust, then spun at 30,000 revolutions a minute. This 'brushes' the dust on to a surface.