The separation is made by observation of inclusions with a microscope. In some cases this is simple and straight forward, but at other times it requires judgment based on experience. If you are a novice gemologist, I hope you have learned two things from this. First, what the basic procedures are to identify gems. While learning gemology is a worthwhile endeavor, you shouldn t make an expensive decision based on limited knowledge.
Most jewelers have limited experience in colored stones.
If they have a Graduate Gemologist degree, that means they are well trained in methodology and the use of instruments. However, their training only covers the 100 or so gems that are most likely to show up in jewelry. If you would like to learn more about gemology, you can contact your local college or university. Some of them have courses available. The Gemological Institute of America has an excellent correspondence course.