(IDEX Online) - Lab grown prices have yet to bottom, and could fall by a further 80 per cent, says one industry expert.The gap with natural diamonds has been widening since labs growns first became mainstream in 2018.In some cases like-for-like lab growns are now just 10 per cent the price of a natural.But Cormac Kinney, CEO of the commodities trading firm Diamond Standard, believes there's still a long way to go. He says lab grown prices could fall by a further 50 per cent to 80 per cent."Fashion jewelry is always worth a small fraction of real jewelry," he told Business Insider. "Only real is rare."Lab growns now account for around a fifth of the total diamond market, with Walmart and Pandora and other retailers offering them at ever lower prices.But the appetite for lab growns may be on the wane, says Kinney, because they hold so little value."Jewelers tell me that a growing number of couples are coming one to three years into a marriage and replacing a synthetic stone with a smaller but real natural diamond," he said.