Emeralds are primarily known for one thing - their signature green color. It's what makes them recognizable and, of course, coveted. If you are considering purchasing this gem, which is the birthstone for the month of May, there are certain things you should know or consider before choosing your emerald.
First, know who you are buying your emerald from. Only deal with reputable and trusted vendors. Preferably, you should purchase from a jeweler you have dealt with before or a jeweler that is highly recommended by an independent party. If that is not possible, do some research to ensure that the vendor you deal with is respected and trustworthy.
Next, take a good look at the stone. Is it too light in color, comparable to a coke bottle perhaps? Then, it might not be an emerald. The color should be a deep, vibrant green.
Keep looking. Does it look brittle? Ask about cracks and other flaws, or "inclusions" as they are known when discussing emeralds. Some inclusions are acceptable as completely flawless emeralds are incredibly rare. Ask the vendor to point the inclusions out. Notice how deep they are. If they are too deep, they run the risk of fracture.
If the price seems too good to be true, it may be. You do not want to purchase an emerald for less than $200/carat because it likely has serious flaws that may actually lead it to crack later on. It doesn't have to be perfect but it shouldn't be riddled with flaws or deep inclusions either.
Ask questions. Has the stone been heated, coated or dyed? Emeralds should never be heat treated. Other stones, such as aquamarine and sapphires, are often heat treated for various reasons, but emeralds should not be. Also, ask if it has been coated with anything. Sometimes, emeralds are coated with resin to reduce the appearance of inclusions. Some enhancement is normal but you still want to ask if it has been coated. You want to know that what you're looking at is the gem as is, without any major enhancements.
Know that the country where the emerald came from doesn't matter. It actually has no bearing on the value of the stone. Rather, the stone itself - its color, its cut, its flaws or lack of, its treatment - are what make an emerald valuable and worth your purchase.
Emeralds come in a variety of cuts. Compare different cuts and see which reflects light the best and most evenly. Largely, it is a personal choice but the most popular is the rectangular "emerald" cut.