Thailand is well known as one of the most important trading centers in the world for colored gemstones. So it is not surprising that many visitors to Thailand -- we get more than 12 million tourists a year -- are interested in buying gems. But it's not as easy as it sounds. In fact many tourists fall prey to unscrupulous con men in an infamous swindle sometimes known as The Thai Gem Scam.

Here's how it works. A tourist sets out to visit one of the well known tourist locations in Bangkok, such as the Grand Palace or Wat Phra Keow, the Temple of the Emerald Buddha. Upon arriving in the area, the tourist will be approached by a friendly well dressed Thai, perhaps a student, who speaks good English. He informs the tourist that unfortunately the attraction he wants to see is closed today because of a special holiday, but there is a tuk-tuk (auto rickshaw) who will take him to a special temple that few tourists have a chance to see.

Upon arriving at the temple, the tourist meets another friendly Thai who strikes up a conversation. In the course of the conversation the tourist is informed about a special government program that allows foreigners to buy gemstones and jewelry tax free and make a profit on the items when they are shipped back home. However, he also mentions that today is the last day of the program.

The unsuspecting tourist who falls for this story is taken to a gems shop where he is pressured to buy stones or jewelry which, he is assured, are of the finest quality. The shop owner insists on cash payment but provides the extra service of packaging up the goods and mailing them to the tourist's home address.

Once he returns home, he discovers the gems are synthetic or of inferior quality, worth far less than he paid. At this point there is little he can do.

Tourist scams are an unfortunate fact of life in many places in the developing world. You can protect yourself by being skeptical when faced with improbable stories about special promotions, and high pressure sales tactics are always a warning sign. Never pay cash for valuable items -- credit cards and electronic payment methods such as PayPal provide an important measure of consumer protection.

Probably the most important thing is to buy from a dealer who has a reputation for honest business. That can be difficult to do when you're a stranger in town, but you can do research on the internet before you leave home. A number of well known gem dealers sell over the internet and in fact you can find the same prices online as you'll find in Thailand, with much less risk.