Ok...So I talked with my appraiser/gemologist today and she said...
1) Look for a brilliant green colour (like Palmolive dish soap...it's a general colour that everyone knows..) If it's VERY light in colour, with a yellow hint, it's not a great stone, and not worth much. Look for darker stones...NOT REALLY dark so you can't see through them. (probably old broken up beer bottles...not good)
2) There WILL be inclusions (cracks) or carbon (black spots) in the stones...this is not a bad thing...but TOO many is. Look for a stone with few cracks or spots....the less the better, and the darker the better. BUT...If you come across a crystal clear stone with NO CRACKS OR SPOTS, and it's not going to cost you thousands of dollars (not pesos), it's a piece of a seven up bottle. Avoid this...you won't be happy with it. Unless you're going for "pretty and sparkly, with no value"...then it's a good thing.
3) The "less the inclusions (cracks), the more expensive...both to buy and appraised when you get home. So more valuable.
4) Try to get a hold of a "loop"....a jewellers' magnifying eyepiece so you can look really close at whatever you are buying. 10X is good, 15-20 even better (the strength of the glass you are looking through). Magnifying glasses from the dollar store just wont cut it...
5) IF you see something you just can't do without, buy it....after all it's you that wants it and will wear it...BUT REMEMBER....YOU ARE IN A FOREIGN COUNTRY, and like everything else you buy, BUYER BEWARE. There are NO warranties or returns, generally on items bought abroad....and what you get when you get home is what you paid for. So just be careful where you buy.
So that's the info I got....Hope it may help. All I can say is go to a jeweller YOU know, and get them to show you some "good" emeralds...NOT the realy expensive ones that you couldn't possibly afford up here..just something "common" Maybe it'll help with a purchase in SAI.
Adam