(CNN) — Asia might be home to some of the world's major gem trading hubs, but for tourists looking to buy precious stones when they travel in the region, fears of fakes and scams can be a huge deterrent.
However, gemologists say there's little to worry about if travelers are careful and heed some basic tips on how to discern real stones from the phonies.
An overview of the main markets
Thailand, Hong Kong and Jaipur in India are three of Asia's key gem trading centers, says Russell Shor, senior analyst for the Gemological Institute of America (GIA), a non-profit organization that specializes in education, research and standards in the gem trade.
Jaipur is India's hub for the sale of gems, which are sold at kiosks, stores and street markets throughout its Old City area.
Jaipur, Bangkok and Hong Kong are the three major gemstone trading hubs in Asia.
While Jaipur's gem trade focuses mostly on lower-end stones, Hong Kong is the region's No. 1 location for expensive gems, including "million-dollar-plus jade and ruby pieces," says Shor.
Why Hong Kong? Tax-free shopping makes it an attractive destination for tourists, who contribute more than US$1 billion a year to its gemstone export trade.
Thailand, meanwhile, is one of the world's top colored gemstone cutting and trading centers, exporting in excess of US$600 million worth of gems a year.
Bangkok's Silom neighborhood in particular is home to hundreds of gem traders, while the town of Chanthaburi in southeast Thailand is a major center for stone cutting and boasts a big weekend gem market.
Most of the gems sold in these three centers are imported from other parts of the world. The leading sources of colored gemstones, such as rubies, jade, emeralds and sapphires, are Brazil, Myanmar, Sri Lanka, Madagascar and Tanzania.
Among the main producers of diamonds are Russia, Australia, Canada, South Africa and Botswana.
Tips and tricks of the trade
Thai gemologist Kanpoj Thanachakaphad hosts workshops to help tourists avoid being scammed.
So how can a buyer know for certain a gem is legit?
Thai gemologist Kanpoj Thanachakaphad, a graduate of the GIA with 15 years of experience in the trade, recently launched a series of workshops to teach tourists how to analyze stones, particularly diamonds.
He says that because Thailand, India and Hong Kong are major gem export centers, they offer tourists better value on stones than they would find in their home countries, which are most likely at the end of the supply chain.
He launched the two-hour workshops after seeing how many tourists were fearful of being sold fake gems by unscrupulous traders.
According to both Thanachakaphad and Shor, there are several key measures tourists can take to avoid being scammed when shopping for gems.
The golden rule, especially when buying expensive stones, is to have them assessed for quality and authenticity at a reliable gem analysis laboratory before purchase.
Gem analysis reports often cost less than US$100 and can be completed within 2-3 days.
Shor says these reports include a "scientific and impartial assessment of the gem." While some glass imitation gems can be spotted easily due to unnaturally-bright colors and small bubbles inside the stone, sophisticated fakes can only be identified by a gemologist, he adds.
Thanachakaphad says the very act of asking to do a lab analysis on a gem would help flush out unreliable traders.
"It shows that you're not stupid, that you know what you're doing," he says.
"If the trader doesn't agree to have the gem tested at a lab then you know they're not honest, and you can just move to another shop. Any honest trader will be happy to have a gem tested if you're a serious buyer."
Thanachakaphad concedes lab reports are not always feasible due to time constraints for tourists, or perhaps the cost may be prohibitive when buying cheaper gems.
If lack of time is the problem, then buyers wanting an expensive stone should hire a consultant from a gem analysis lab to provide on-the-spot advice.
In other cases, Thanachakaphad says there are several ways to avoid buying fake gems and get the best price on real stones:
Real diamonds' color should be stronger when you look at it from the back, instead from the front.
MIKE CLARKE/AFP/AFP/Getty Images
Learn the lingo
Pick up some basic terms relating to gems, particularly the type of stone you're interested in, and use them in conversation with a seller to show you're not an easy mark.
If you have done some basic research about a particular gem you will be able to ask the seller about things like its cut, color, clarity and source.
Look out for fakes
Fake gemstones often have shadowing (double lines) along each of their cuts. Real ones don't.
When assessing diamonds, a real stone's color should be stronger when you look at it from the back. Fake diamonds tend to have brighter colors when you look at them from the front.
Don't be afraid to ask to see the gemologists for their qualifications when in doubt.
A wide product range?
Untrustworthy gem shops often have very big product ranges, trying to distract you with their variety. Reliable shops typically have smaller ranges.
Don't trust tour guides and taxi drivers
Avoid dealing with gem traders recommended by a tour guide, a taxi driver or a tout. These people normally get paid hefty commissions to bring you into an unreliable gem shop.
Compare prices and sale tactics
If you want to shop for gems by yourself, make sure you visit several different stores to compare prices and also to note the behavior and sale tactics of the staff in each shop.
You will start to identify patterns of behavior, which will help you avoid being scammed.
Ask to see qualifications
Before you travel to a city to buy gems, research reviews of shops online to find the best-regarded traders.
When in doubt, pick a shop staffed by trained gemologists with qualifications from GIA or other renowned institutes. Ask to see their qualifications.