Here is a question from one of our customers:
Q: May I know what is the difference between gemstone pendant and crystal pendant ?
Your question has to do with how crystals are rated or graded. In order to be considered gem quality a crystal or stone is rated by its characteristics. Color, Clarity, Cut and Carat(size). The chart below is example of grading.
Another factor in price that has nothing to do with grade is the rarity of the crystal or stone. A crystal or stone can be low grade, but if it is rare or difficult to find it can be higher priced then a perfect gem.
That in a nutshell is the answer to your question. If you are a serious collector, grading can be important, if you collect just for fun it may not be as important.