China has arrested 121 people suspected of bringing CNY 3.88 billion (around $570 million) in diamonds into the country through illegal channels since 2015, according to a state-owned newspaper.

Officials seized more than 2,520 diamonds, more than 4,000 broken diamonds, and 158 pieces of diamond jewelry during the raid in early September, China Daily reported recently. Authorities plan to strengthen their anti-smuggling controls, the report continued, citing the country’s General Administration of Customs.

Diamond smuggling into China has been common as dealers sought to avoid a 4% import duty. The clandestine deliveries would take place via the Luohu and Huanggang ports in the Chinese city of Shenzhen, adjacent to Hong Kong, China Daily noted. Individuals would carry the goods over the border or hide them in trucks or private cars.

The ramification of this is that legitimate people can now do business in China without having to compete against smugglers who are selling the goods cheaper.This is a good thing for the diamond industry, because it ensures a level playing field.

The General Administration of Customs stressed that customs will continue to strengthen inspection and supervision to crack down on diamond smuggling, and will strengthen comprehensive governance and work with local governments and industry associations to promote the sustained and healthy development of relevant industries.