(IDEX Online) - Lab growns are the biggest threat to Namibia's diamond industry, according to Namdia, the state-owned trading company.Lelly Usiku, executive market development, sales and brand says they are increasingly popular in China, the biggest retail market after the US.Lab growns are filling a gap left by Alrosa's reduced production, following its invasion of Ukraine, she said, according to a report in Namibia's Windhoek Observer newspaper.Usiku also said consumers in the US were moving towards lab growns because of high inflation and interest rates.She noted that lab growns now cost from 60 per cent to 80 per cent less than Namibia's natural diamonds