TAIPEI (Taiwan News) — The Ministry of Foreign Affairs (MOFA) cautioned travelers against taking gold and jewelry to Japan on Thursday (July 4) after customs confiscated a necklace from a Taiwanese visitor last month.

The traveler was detained at the airport for six hours and had to give up a necklace containing 3.5 Taiwan Tael, or 131.25 grams of gold, as well as a phone, per CNA. Officials named the falling value of the Japanese yen, the rapid rise in gold prices, and a hike in Japan’s consumer tax to 10% as the main causes behind the incident.

The shifts mean that the value of jewelry can easily exceed the 200,000-yen limit (NT$40,269, US$1,240) above which travelers have to report their valuables, said Fan Chen-kuo (范振國), the secretary general of MOFA’s Taiwan-Japan Relations Association (TJRA).

Japanese customs officials reportedly concluded that the Taiwanese visitor planned to sell the jewelry rather than just wear it. Japan has recently taken an interest in these cases of gold smuggling, and the traveler should have filled out a form about the value of the jewelry during the flight or just before passing through customs at the airport, Fan said.