Rapaport Diamond Report is highly recommended to subscribe to for any diamond dealer. It is the opinion of the author that much of the list is overestimating but it is still an excellent source to refer to on a regular basis. Using this publication along with reliable diamond dealer inventory lists and experience will give you a clear picture of current diamond values. The Guide also offers a diamond price guide, based on real selling prices. Contact information for these subscriptions is in the back of the course material.