Gems should never be bought because of a low price or because they look pretty, the consumer will always loose.    Before you buy familiarize yourself with the gem.  The average person can't make the same judgments as a qualified gemologist who has training and practical experience, but you can learn what factors to look for such as color,cut,weight,and brilliance.   Before you invest your money no matter how little or how much spend your time to find out all you can about the gem. If a gem is cut wrong it won't fit into any settings and to have something custom made for it could cost more then it will ever be worth. How hard is the gem? If to soft it will break when set, some gems fade in sunlight will this gem be one to do that? Is the color the best for that price? There are five things to look for and you need to ask yourself 1 Is this the color you want? 2 Does the color have loveliness and zip ? 3 What shape do you want? How will it be used?  4 Is the price right? 5 How well do you like it? When you look  at a gem there are ways to look at it. If you can look at the gem unmounted, make sure it has been cleaned so there is no grease or dirt on the gem,  hold the gem with tweezers [if you know how to use them], if not hold it on the side of the gem this is called the girdle of the gem. View the gem under different lights, diamonds will show more fire under fluorescent and rubies will look better under sunlight. Rotate the gem  and look at it every way. Use a Loupe[special magnifying glass that you can use to check for chips or scratches] Find out what is a natural inclusion for the gem ,known as the finger print of the gem.  [Inclusions can be can be black spots, lines, bubbles, sun spots, marks or crystal] Check if the gem is well cut because it will affect the value of the gem. The way a gem is cut will make a difference between a brilliant gem or a lifeless gem. Look at a gem face down does the color look good every way you look or are there dead spots? How is the color is it to light or to dark? What about the cut of the gem what is the cut you like? different cuts will affect the way a gem looks,but for the average person it is what shape do you like? If a gem is well cut the value and beauty will endure, Take time as you shop for gems to check them out in a jewelry store to see how they should look. Remember you are not a expert so decide to do business with someone who has knowledge and integrity so you don't make a costly mistake.