By Tu Lei

A senior official from the State-run National Gemstone Testing Center said Wednesday that it will sign a cooperation agreement with Hong Kong-based Chow Sang Sang Jewelry next week to ensure its products' quality.

The stepped-up cooperation comes amid public concern over the amount of gold contained in jewelry sold by Chow Sang Sang.

"In the past, only a portion of their diamond products underwent testing (with us), but now the test will cover all of their products, and only jewelry that passes our tests can be sold," Bi Lijun, director of National Gemstone Testing Center, told the Global Times.

The issue arose after the Beijing Administration for Industry and Commerce recently said a popular style of the jeweler's 18K gold bracelets failed to pass gold-purity tests, leading to 50,000 pieces being pulled off shelves.

"The per-piece testing fee for gold is less than 10 yuan ($1.5), and 10-odd yuan per piece of diamond jewelry," Bi said, adding that the cost is just a fraction of the usual prices of the items, which run into the thousands of Hong Kong dollars. He added that rival jeweler Chow Tai Fook already uses the testing center to verify quality.

Chow Sang Sang is one of the biggest jewelry retailers in China. It has opened nearly 300 stores on the Chinese mainland since the business started in 1994.

After seeing its stock price tumble 10.5 percent Monday, shares saw a slight increase of 1.09 percent to HK$18.60 Wednesday.

The well-known jeweler announced Friday that buyers of questionable 18K gold bracelets will receive a full refund if the original receipt is presented at any Chow Sang Sang store on the mainland until December 31.

A shop clerk named Dou Yuehong at Chow Sang Sang's flagship store in Beijing's Sanlitun area said all their 18K gold jewelry, including pendants and necklaces, had been pulled off shelves to undergo quality inspections. She did not say when they would be back on sale again.

"If the customers have concerns over other 18K gold products, the company will still offer a full refund," Dou said.

However, Liu Yongbin, a lawyer at the Beijing-based Yingke Law Firm, said Wednesday that the Chow Sang Sang may have committed fraud, since a discrepancy was found between its gold purity claims and actual tested purity.

Liu, therefore, contended that buyers of the firm's 18K gold should be entitled to double their money back, according to the Consumer Protection Law.

Chow Sang Sang said in an e-mailed statement to the Global Times Wednesday that no government department has accused the company of fraud.

"Our company will strictly follow the letter of the law in dealing with customer requests," the statement said.