Listen to your jeweler. Only a master jeweler will have the most valuable advice in your search for the perfect gem.
Learn as much as you can about the jewelry you are interested in, so you can make an educated and informed decision.
Look at your gem before you buy it. Good jewelry is meant to last a lifetime, don't be fooled by mail order dealers. Viewing your gem in person is the best way to make sure you are getting the stone that's perfect for you.