Luk Fook saw same-store sales drop by as much as 10 percent year on year in the first quarter of 2014, which Wong attributed to the fluctuating price of gold once the top item on mainland tourists' shopping list. "As the comparison base is high, this April won't be any better," he warned.

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"Golden week used to be the big thing of a year when it was rolled out a decade ago," Wong said. "But now it has been normalized fewer people are visiting Hong Kong during the holiday. Holiday sales are only 40 to 50 percent higher than average days."

That was echoed by a spokesperson for Chow Tai Fook, another major jewelry store in town. "The golden week effect has faded in the recent years. Nowadays, mainland tourists tend to visit regularly. From May 1 to 4 this year, sales in our chain were similar to that of ordinary weekends. And it is in line with what we expected."

But the Travel Industry Council's Tung said the greatest loss is the erosion of high-end visitors.

"In the recent years, we have witnessed more and more mainlanders turning to Europe and the US to buy luxury goods, because money-wise, our edge is declining. People can get branded handbags and shoes at bigger discounts in the countries of origin. Now, even fewer will come as mainland tourists discover Hong Kong treats them without respect. And they have plenty of other choices," he said.

Tung said he is worried that such behavior will cast a pall over Hong Kong's image to the whole world.

"Hong Kong is known as a friendly city worldwide. However, excessive actions targeting mainland tourists may also deter visitors from other countries. That will put Hong Kong in an even worse position," Tung said.