The local laboratory of the National Gemstone Testing Center refused to tell which countries the stones came from, or which were the source of the most problems.

    It did say that many travelers bought artificial stones thinking they were real, and emeralds were the biggest problem.

    The newly opened laboratory offered to test jewelry for free last month. Of the 1,716 pieces tested, 485 were bought by tourists, either in other parts of China or oversees. The lab said only 51 percent of the jewels bought by tourists were as valuable as buyers believed.

    It didn't say how many of the problem jewels were bought it China.

    All 26 pieces of emerald sent for testing proved to be man-made fakes, the lab said. It said only two of 45 pieces of jewelry bought in Southeast Asian countries contained real stones.

    Most of the problem jewels were bought in small stores, the lab said, adding that large department stores and brand-name jewelry stores were much more dependable.

    "Some stores will also give certificates with grades like B or C for the emeralds, which is an irregular practice and misleading," said Sun Xiaofei, a lab official.

    Stones with B or C grades are actually dyed or blanched jewels of poorer quality, but the shop assistants will tell buyers they are just a little worse than the grade A stones. 
    
    (Source: Shanghai Daily)