(IDEX Online) - More than 100 people have reportedly been arrested on suspicion of conspiring to receive diamonds smuggled from Hong Kong to the Chinese mainland.A Chinese couple had 150 packets of undocumented polished diamonds and details of their destinations when they were picked up in the border metropolis of Shenzhen (pictured), a special economic zone which is home to more than 2,300 cutting and polishing units. Their information they yielded is said to have led to the arrest of 120 Chinese nationals, alleged to be have planning to receive the gems.Diamonds legally imported into China attract a four per cent customs duty, which smugglers try to evade.In January 2010, nine Indian diamond merchants received jail terms of six months to six years in Shenzhen for smuggling polished diamonds worth $7.3m.