The appraisal discipline is actually separate from gemology. Commonly the assumption is that a Graduate Gemologist degree is enough qualification to determine value. In fact I too had this assumption leaving gemology school. I quickly learned of the years of appraisal education that were ahead of me. Let me explain the difference. A gemologist has the skill to properly identify gem material, quality grade and evaluate jewelry before a value is set.  An appraiser uses principles and methods to calculate value based on gemological grading, quality of materials and the appropriate market. To become an appraiser involves years of additional education, experience and ongoing research.