Research the market before you arrive. Check the standard wholesale rates for gemstones, and find the prices for stones sold at retail outlets in the United States and from reputable online sources. This is the only way to determine if the Thai stones are worth the time and trouble it takes to buy them.
Check out the sellers by talking to people you trust, and those experienced in dealing with him or her. Learn the price of gemstones by quality and weight, measured in carats, in Thailand. Don't wander into a shop without advance knowledge of what they sell, their reputation, and the general market price of the gemstone that interests you.
Visit the lower Silom Road area in Bangkok, where shops by the hundreds stand ready to sell you gemstones. This area is probably the safest for buying gems, as the proprietors are cautious about their reputation and want to avoid trouble with buyers. However, be aware that as businesses they seek to make the most advantageous deal for themselves, and aren't necessarily out to provide you with a bargain.
After entering a shop, examine the merchandise without selecting any particular stone of interest to you. Inquire about market gem rates, the origin or provenance of the stones, the cutting and polishing process and how to judge authenticity. Before making any inquiries about a particular stone, make small talk and get a sense of the dealer's interest in helping you. If you feel rushed, politely leave.
Request the dealer's price if it is not displayed, and only for stones that attract you.
Haggle with the dealer only if you're truly interested in the stone and are prepared to buy it. Offer a reasonable price that is below the dealer's quote and gauge the dealer's reaction. Once you reach an agreed-upon price, you will be obligated to buy unless you're prepared for a rather awkward situation.
Ask for a dated receipt and a certificate of authenticity after the purchase. The paperwork will assist you if any problems arise.
