A man and a woman suspected of stealing a valuable ruby with the old switcheroo were arrested on Saturday.
The alleged theft took place at the Hong Kong Jewellery & Gem Fair at the Convention and Exhibition Centre in Wan Chai last week, according to Apple Daily.
The woman, a 45-year-old surnamed Fan, asked an exhibitor to display the ruby, worth HK$1.17 million (US$149,000), while the man, a 47-year-old surnamed Zhang, asked to see diamonds on the other side of the booth. The woman then replaced the ruby with a fake stone.
Staffers alerted police on Friday. Fan was arrested Saturday afternoon, and Zhang was arrested several hours later at the Lo Wu immigration control point in the New Territories.
HK01 reported that police found 34 gems in the trunk of his car, 16 of which were believed to be stolen from the jewelry show.
Both suspects are from Yunnan on the mainland, and hold two-way permits for entering and exiting Hong Kong.