International Cricket Council (ICC) chiefs believe floodlit, day/night Tests could take place in the next few years but insist more work needs to be done on the ball before they give the go-ahead.
A traditional red leather ball is difficult to see under floodlights, while the white ball used for day/night one-day internationals doesn't wear at the same rate and so is considered unsuitable for longer formats.
Finding a suitable ball has so far proved the key stumbling block, with David Richardson, the ICC's general manager for cricket, telling reporters at Lord's on Wednesday: "We've spent a lot of time over the last 24 months trying to develop a ball.
"Now we've crystallised that there's not much difference between the pink and orange balls and it was a question of finding a ball that could retain its colour throughout 50-80 overs."
Richardson was speaking after a two-day meeting of the ICC's cricket committee at Lord's, the self-styled 'home of cricket' and the headquarters of Marylebone Cricket Club (MCC), who a