1." Experienced diamond dealers and gemstone dealers do not need ANY equipment to identify diamonds and gemstones. Most of them also do not have formal education and some of them cannot read, but they are very good at what they do – diamonds and gemstones. "
With all due respect, this statement is inaccurate, to say the least. Even the most experienced dealers cannot separate natural colored gemstones from their better lab-created counterparts without the help of an experienced gemologist - with good gemological equipment - or without the use of the services of a gemological laboratory; this is especially true for identifying expensive gemstones like emeralds and rubies.
Also, many enhancements - for diamonds and colored stones - cannot be detected without good training and good gemological equipment. What good is it for a dealer to be able to identify a diamond or a ruby for example, if he/she cannot identify a potential treatment that could make a huge difference in the value of the stone?
"Somebody mentioned that it cannot tell synthetic stones from real ones – actually – no tester can and most people cannot, many trained people cannot, that’s not a tester’s fault. Synthetic stones (the ones created in the lab, like synthetic ruby, which has same properties as genuine one) are not easy to detect."
I agree. However, an experienced gemologist - with good gemological equipment - has a good chance at separating a natural gemstone from it's lab-created (synthetic) counterpart. With a Presidium Gem Tester, you don't have a prayer!